Video (YouTube): How to Fix a Computer that Won't Boot Up (Official Dell Tech Support)
1. Verify the Computer Finishes Initial Power-Up (POST)
In many cases a computer will not attempt to hand off control to the operating system. If you power the computer on and you see a Dell logo screen with a bar at the bottom, and that bar fills up completely and disappears, then your computer has successfully completed POST.
A piece of hardware may be interfering with the normal boot process of Windows. Try unplugging all devices from your computer, including:
Media Card Readers
Small Media cradles (iPod, PDA, MP3 player, etc.)
Digital Cameras and Video Recorders
USB storage devices
CDs or DVDs from all optical drives
The only devices you should leave attached to your computer are your monitor, mouse and keyboard, if the computer is a desktop.
Once this is completed, unplug the computer from the wall, remove the laptop battery (if applicable) and hold the power button down for approximately 15 seconds. Then plug wall power back into the computer and attempt to restart.
If your computer is set to first attempt to boot to another device, this may cause issues with successfully booting to Windows. To reset your computer's BIOS to factory defaults, perform the following steps:
Restart the computer.
At the Dell logo during restart, tap the F2 key repeatedly until you see Entering Setup in the top right corner of the screen.
Depending on the BIOS, you may need to press a key listed at the bottom of the screen to load default settings. For example, F9 on the Inspiron N5110.
Press ESC to exit the BIOS, and be sure to select Save and Exit to save your changes.
Note: If resetting the BIOS to factory defaults does not resolve the issue, you may also try to update the BIOS to the latest version to resolve issues related to the BIOS of your PC or tablet. Refer to the Dell knowledge-base article What is BIOS and How to Download and Install the latest BIOS? for more information on BIOS update or downgrade procedure.
Note: System BIOS may get corrupted if the BIOS upgrade or downgrade procedure is not completed successfully or interrupted.
A corrupt BIOS is one of the possible causes of your PC unable to complete POST or some times even boot into the operating system.
If your Dell PC or tablet supports BIOS recovery, you can recover the corrupt BIOS by using the BIOS recovery method applicable for your Dell PC or tablet. Refer to the Dell knowledge-base article BIOS Recovery options on a Dell PC or Tablet for more information.
5. Boot to the Hard Drive Using the One-Time Boot Menu
Restart the computer, and at the Dell logo screen tap the <F12> key multiple times to invoke the One-Time Boot Menu. Select the Boot from Hard Drive option and press Enter.
6. Run a Computer Diagnostic
To run PSA Diagnostics, turn on the computer and tap the F12 key several times at the Dell logo screen. This will start the One-Time Boot Menu. Select Diagnostics to start the diagnostic assessment of the computer hardware.
This test takes approximately 5 minutes.
If you receive an error from the PSA diagnostics, refer to the Dell Hardware Diagnostics page for further assistance:
Tap F8 on the keyboard immediately after the Dell logo screen disappears until you see the Windows Advanced Options Menu on the screen. (If the Windows Advanced Options Menu does not appear, restart the system and try again.)
Select Safe mode and press Enter.
Log on as the administrator or as a user with administrative access.
If your computer does not boot to Safe Mode, select from the following options to troubleshoot. Otherwise, proceed to Step 5.
8. Attempt to Boot to the Last Known-Good Configuration
The Last Known-Good Configuration can help you reestablish the settings that your computer used the last time that you successfully booted to Windows. To invoke the Last Known-Good Configuration, perform the following steps.
Power on the system.
Press < F8 > when the message For troubleshooting and advanced startup options for Windows, press F8 appears.
Choose Last Known-Good Configuration
9. Check for Recent Changes
If you are able to successfully boot to Safe Mode, check your computer to see if any new software or hardware was recently installed. If so, try uninstalling those programs or hardware from your computer.
10. Use Startup Repair to Restore Critical Windows Files
Startup Repair is a Windows 7 recovery tool that can fix certain problems, such as missing or damaged system files, that might prevent Windows from starting correctly. When you run Startup Repair, it scans your computer for the problem and then tries to fix it so your computer can start correctly.
11. Use System Restore to Revert to a Previous State
Click here to watch a video on how to use System Restore in the Windows Recovery Environment (WinRE). (Note: English Only)
Note: If the Windows Advanced Options menu does not appear, restart the computer and try again.
Note: Attempt to restore from the most recent restore point. If this fails to correct the problem, try the next most recent restore point until you find a restore point that resolves the issue. You will need to reinstall any software installed after the selected restore point.
Restart the computer.
Tap <F8> during startup until the Windows Advanced Options menu appears.
Press <Down Arrow> until Repair Your Computer is highlighted, and then press <Enter>.
In the System Recovery Options window, click to select your language, and then click Next.
Log in as a user with administrative rights, and click OK.
From the Choose a recovery tool menu, click System Restore.
In the System Restore window, click Next.
Click the Show restore points older than 5 days checkbox for a complete listing of restore points.
Click to select a restore point.
Click Next and then click Finish.
Click Yes in the confirmation window.
Click Restart after system restore successfully completes.
If you encounter any error messages during the restore process, follow the on-screen instructions to correct the error.
12. Use Clean-Boot Troubleshooting to Isolate the Software Issue
Video (English Only): Perform a Clean Boot to detect Software Problems
A program or application may be interfering with the normal boot process of Windows. Microsoft has created a detailed process for isolating a startup program that is causing Windows to not boot correctly. Click the link below to being the troubleshooting process:
14. Restore the Operating System to Factory Settings
If clean boot troubleshooting cannot identify the issue, it may be necessary to restore your computer to factory settings. To restore your computer's operating system and software to the original factory settings, launch the link below: