I had an issue with a graphic driver after an automatic update! The screen was black but the rest of my Windows worked fine. Usually you would boot in Safe Mode and restore the former driver or deactivate the VGA Card or something similar to the same effect. So that was my struggle because I couldn’t get into Safe Mode anymore.
The only solution that worked for me was using the Windows 8 Install DVD!
Insert the DVD and boot from the DVD. (Eventually you have to press a key depending on your PC that enables booting from a DVD).
Windows will now boot from the DVD.





Change to your Windows Installation Partition. Usually the C:\ drive.
Now Enter the following command:
bcdedit /set {default} bootmenupolicy legacy
Hit enter and it should return a successful message in the prompt.
Write exit or simply reboot the computer.
Now the legacy startup options are enabled and you can simply hit F8 during startup.
The previous startup selection screen will then be displayed, where you can choose your desired startup mode.
Finally you can actually start with the debugging of the problem.
Good Luck.