What to do when your computer won’t start

You sit down at your computer, push the power button just like you do every day, and… nothing happens. Maybe the computer doesn’t turn on at all, or it could power up but shut right back down. As far as you’re concerned, there’s nothing obviously wrong here, so why won’t the computer just start?

Before you start panicking or looking for a new laptop to buy, let’s first rule out this isn’t something you can’t fix yourself. Here are some troubleshooting steps to take that can help narrow down the issue.

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1. Give It More Power

Are you sure the computer is charging(Opens in a new tab)? If the machine isn’t turning on at all—no fans are running, no lights are blinking, and nothing appears on screen—you probably have a power issue.

Unplug your computer and plug it directly into a wall outlet you know is working, rather than a power strip or battery backup that may be failing. Make sure the power switch on the back of your power supply is flipped on, and if the outlet is connected to a light switch, make sure that switch is turned on too.

If you’re using a laptop, make sure your charger is plugged in properly and to the correct port—if it charges via USB-C(Opens in a new tab), only some of the USB ports may actually provide power. A failing power supply can often cause boot problems, even if the fans and lights do turn on. So if the troubleshooting steps in this guide fail you, it might be time to replace your power supply.

2. Check Your Monitor

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If the computer sounds like it’s turning on but you don’t see anything on the screen, the computer may be booting and the monitor just isn’t showing an image(Opens in a new tab). Check to make sure your monitor(Opens in a new tab) is plugged in (again, try a wall outlet instead of a power strip), turned on, and set to the right input using the buttons on the side or bottom.

Make sure the cable connecting the monitor to your computer hasn’t come loose, become damaged, or is in any way at fault. You also want to rule out a problem with the monitor, so try plugging your PC into another display — or even a TV (Opens in a new tab)— and see if you can get a picture that way. If you can, it’s possible you need a new monitor(Opens in a new tab).

And this may sound silly, but make sure the brightness is turned up on your laptop. I’ve had multiple people ask me for help with a computer that won’t start, only to find the brightness was turned all the way down, creating a black screen.

3. Listen for the Beep

When your computer boots, it may make a beeping sound—usually a single beep means everything is A-Okay. But if the computer is having trouble starting up, it may make a series of beeps (kind of like Morse code) that tell you what’s wrong.

Check the manual for your computer (or the PC’s motherboard(Opens in a new tab), if you built it yourself) and figure out what the beeps mean. If you don’t have your manual, you can probably find it on the manufacturer’s website.

If your computer doesn’t beep at all, you might be out of luck, though some desktop PCs may have a header on the motherboard where you can install a cheap speaker(Opens in a new tab), or even a digital display with a numerical code that corresponds to an error message.

4. Unplug Unnecessary USB Devices

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Before continuing, unplug anything superfluous from your computer — webcams(Opens in a new tab), USB headsets, external hard drives(Opens in a new tab), etc. Try booting with just a keyboard and mouse (or even without them, if in dire straits) to see if one of your USB devices is causing a conflict.

In some circumstances, it may not even be the device itself, but the port on your computer(Opens in a new tab). I’ve owned a PC that couldn’t get into Windows if something was plugged into the front USB port—once booted, the ports would work fine, but it needed to be empty during the boot process. The more variables you can eliminate, the better.

5. Reseat the Hardware Inside

There’s a chance a component of your computer has come loose inside the case, especially if it was recently transported somewhere or if you were working inside of it. If you’re comfortable opening your computer up, remove the side panel and make sure the components are properly seated in their respective sockets.

Pay special attention to components like your RAM(Opens in a new tab), graphics card(Opens in a new tab), motherboard cables, and heatsink. Remove these items completely, then plug them back in, ensuring they click in all the way.

You might also try booting without certain hardware, like the graphics card or one of the RAM sticks, in case they’re faulty. (And if it doesn’t work with one RAM stick, try the other.)

6. Explore the BIOS

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If your computer turns on and you see the POST screen(Opens in a new tab) but can’t boot into Windows, certain settings may be causing a problem. For example, an error stating that your computer can’t find a bootable operating system may mean your BIOS is set to boot from the wrong drive or your overclock settings are causing the computer to blue screen immediately.

Enter your BIOS(Opens in a new tab) when the POST screen appears, usually by pressing Delete, F2, or some other key to enter setup. If you’ve tweaked any of these settings recently, try changing them back.

Make sure your Boot Order is set to the correct hard drive, your RAM is recognized, and that your CPU isn’t overheating(Opens in a new tab) (if it’s above 90 degrees Celsius in the BIOS, something is definitely wrong). You might also turn off the Fast Boot feature, in case a recent Windows Update is conflicting with it.

If all else fails, try resetting your BIOS settings across the board using the Load Optimized Defaults option. Just be sure to snap a few photos of your BIOS settings so you can set them back if that doesn’t work.

7. Scan for Viruses Using a Live CD

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It’s possible you have some nasty malware(Opens in a new tab) that’s preventing your computer from booting. But with a live environment like Hiren’s Boot CD(Opens in a new tab), you can boot your computer from a CD or USB drive and scan your hard drive for malware without booting into Windows.

Download the ISO image from this page(Opens in a new tab), and follow the instructions(Opens in a new tab) to “burn” it to a USB flash drive. Reboot your computer and access the Boot menu—usually by pressing F11, F12, or some other key defined at startup. Choose your USB drive from the boot menu, and it should boot into Hiren’s live environment.

From there, you can head into Utilities > Security and run a virus scan with ESET(Opens in a new tab) and a malware scan with Malwarebytes(Opens in a new tab). If either program finds anything, it’ll let you know and attempt to fix it, which will hopefully allow you to boot into Windows once again.

8. Boot Into Safe Mode

If you’re getting the Blue Screen of Death at startup, it could be a result of a bad application, driver issue, or other hardware quirk causing problems on boot. If you can, do a web search for the stop code that appears and see if it gives you any insight into what’s wrong.

Chances are, though, you’ll have to boot into Safe Mode(Opens in a new tab) to fix the problem. This used to be an easy process in Windows 7, because all you had to do was press F8 as you booted up. It is much trickier in newer version of Windows, but usually if you interrupt the boot process three times—say, by pressing the reset button as Windows tries to boot—it will take you to the Automatic Repair screen, where you can click Advanced Options.

Alternatively, you can create a Windows installation drive(Opens in a new tab) using another PC and boot from that directly, choosing your language and selecting Repair Your Computer when given the option. Either of these methods should eventually get you to the Choose an Option screen, where you can click Troubleshoot > Advanced Options > Startup Settings and reboot the computer. (If you don’t see the Startup Settings option, you may need to click See More Recovery Options along the bottom.)

Your computer should then give you the option to boot into Safe Mode, Safe Mode with Networking, or Safe Mode with Command Prompt. You can try any of these, though Safe Mode is probably your best bet, or Safe Mode with Networking, if you need to access the internet. This will load Windows with only the most crucial drivers and services running.

If you installed any new hardware recently, try uninstalling its drivers from Safe Mode. If you think a new application might be to blame, get rid of that too. BlueScreenView(Opens in a new tab) can help you look back through your most recent Blue Screens of Death to see the file that caused the problem, or any bug check strings and codes to look up. 

9. Roll Back a Problematic Windows Update

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If you recently installed a Windows Update—or you think Windows may have done so in the background without you realizing—it may have caused a conflict that rendered your computer inoperable. It’s annoying, but Windows does offer the option to roll back to the previous version(Opens in a new tab), even if you can’t get into Windows itself.

Head back to the Troubleshoot > Advanced Options menu using the instructions above, then choose Uninstall Updates. Try uninstalling the latest Quality Update, or Feature Update. If you’re lucky, this may get you back into Windows, at which point you can delay Windows updates(Opens in a new tab) until the kinks are worked out.

10. Check Your Hard Drive for Corruption

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It’s possible some data on the drive is corrupt, preventing Windows from booting properly. Thankfully, Microsoft has a few tools that can attempt to fix the problem. Head to the Troubleshoot > Advanced Options menu as described above and choose Command Prompt.

Type sfc /scannow and press Enter. Windows will check your drive for corruption and attempt to repair any problems. You can also try the chkdsk C: /r command, which will do a broader search for file corruption and bad sectors.

(If you have multiple drives, you may want to run wmic logicaldisk get volumename,name and replace the drive letter with the correct one from the resulting list.)

11. Repair a Busted Bootloader

Sometimes your Windows installation is fine, but the bootloader — the data that governs Windows’ boot process—is corrupted. This often happens if you clone your hard drive(Opens in a new tab) improperly, in which case you can try the cloning process again, making sure to clone the entire drive, not just the partition where Windows resides. 

It can also happen if you try to dual-boot Linux or create new drive partitions(Opens in a new tab) and mess something up along the way. You’ll often get a message saying “Error loading operating system,” “Invalid partition table,” or “FATA: No bootable medium found! System halted.”

If you have a good backup(Opens in a new tab), you can try to repair the bootloader using Windows’ built-in tools by going to Troubleshoot > Advanced Options as described above, then choosing Startup Repair. I wouldn’t attempt these steps unless you have your files backed up(Opens in a new tab), as messing with partitions can always risk the loss of data.

You can also run the Command Prompt from this menu and try running one of the following commands:

bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd

If that doesn’t work, repairing your bootloader may be more complicated due to newer EFI bootloaders — you can see instructions on doing so here (Opens in a new tab)— but it may be easier and faster to reinstall Windows from scratch and restore from your backup.

12. Test the Drive in Another PC and Pray

If all else fails, and you don’t have a backup, take your hard drive out of your computer, connect it to a USB adapter(Opens in a new tab), dock(Opens in a new tab), or enclosure(Opens in a new tab), and plug it into another known working PC. (Or, if you don’t have another PC, try booting from a Linux Live CD(Opens in a new tab) on your current machine.)

As long as the drive is still working—a big “if”—you can at least copy your files onto an external drive for safekeeping before you reinstall Windows or send the PC in for repairs.

This article originally appeared on PCMag.com(Opens in a new tab), Mashable’s sibling site. PCMag.com(Opens in a new tab) is a leading authority on technology, delivering Labs-based, independent reviews of the latest products and services.