Fix a Windows Computer That Won't Start

Repair a Windows PC that fails to boot. Follow these steps to diagnose and fix startup issues from safe mode to hardware checks.

1. Force shut down and restart the computer. Hold the power button for 10 seconds until the computer powers off completely. Wait 30 seconds. Press the power button once to restart. Watch for signs of life—fans spinning, lights on the case, or hard drive activity. If nothing happens, move to step 2. If the computer restarts, allow it to attempt a full boot.
2. Verify power delivery and hardware connections. Check that the power cable is fully seated in the power supply and wall outlet. Press the power button and listen for the power supply fan to spin immediately. Reseat the RAM by opening the side panel, locating the RAM sticks, pressing the clips on both ends, and firmly pushing the RAM back into the slots until the clips snap. Reseat the hard drive or SSD by disconnecting its power and data cables, waiting 10 seconds, and reconnecting both cables firmly.
3. Access the BIOS startup menu. Restart the computer. Immediately after the screen turns on, repeatedly press the key for your system's BIOS menu—usually Delete, F2, F10, or F12 depending on your motherboard manufacturer. Hold the key down rapidly until the BIOS setup screen appears. This confirms your motherboard and processor are working. If you cannot access BIOS, power failure or hardware failure is likely—proceed to step 7.
4. Check the boot device order in BIOS. In the BIOS menu, navigate to the Boot menu using arrow keys. Verify that your hard drive or SSD appears in the boot order list. If it does not appear, the drive may be failing or disconnected—return to step 2 and check all connections. If the drive is listed but appears with an error code or warning, the drive is likely failing. Reorder the boot devices so your drive is first in the list. Press F10 to save and exit BIOS.
5. Attempt to boot into Safe Mode. Restart the computer. If Windows displays a logo or boot screen, repeatedly press F8 or Shift+F8 before the Windows logo fully loads. If you see the Advanced Boot Options menu, select Safe Mode with Networking and press Enter. If Windows loads in Safe Mode, the issue is a driver or software conflict—proceed to step 6. If you cannot reach this menu, restart and hold down the power button for 10 seconds. Repeat this three times. On the fourth restart, Windows will offer Automatic Repair or Advanced Startup Options.
6. Repair Windows using Startup Repair or System Restore. If you reach Advanced Startup Options, select Troubleshoot, then Advanced options. Choose Startup Repair and let the tool scan and repair corrupted system files. If Startup Repair completes without fixing the issue, go back and select System Restore instead. Choose a restore point from before the problem started and confirm. Windows will restart and revert to the previous system state. If both tools fail or if you are in Safe Mode, restart and try step 7.
7. Reinstall Windows using installation media. On another computer, go to microsoft.com/software-download and download the Windows installation tool. Create a bootable USB drive following the tool's instructions. Insert the USB drive into the non-booting computer, restart it, and immediately press the BIOS boot key. Select the USB drive from the boot menu. When the Windows Setup screen appears, select your language and click Install now. Follow the prompts, select your drive, and choose to keep your files or perform a clean installation. Installation takes 20 to 40 minutes.
8. Confirm successful startup and update drivers. After Windows boots, log in and verify all components are recognized in Device Manager. Right-click the Start button, select Device Manager, and look for any devices with yellow warning icons. For each warning, right-click the device, select Update driver, and choose Search automatically for updated driver software. Allow Windows to search Windows Update for the latest driver. Restart the computer once all drivers are updated. Run Windows Update to install any pending system updates.