After changing Video settings or drives your screen can adjust beyond the limits of your monitor. To get back to a setting the you can see follow the steps below and adjust the settings appropriately.
Hit F8 as soon as the Starting Windows splash screen appears to get the the boot options menu. If the menu does not appear power down the PC and try again, F8 needs to be pressed as soon as the splash screen appears.
From the boot options menu select VGA mode.
If the Video setting were the problem Windows should boot but the resolution and color depth should be lower.
Once Windows boots you have a few option depending on what caused the problem.
If The resolution was set too high you can adjust the resolution to a lower setting and reboot to test the new settings.
If Vidoe Drivers caused the problem you can do the following:
Click Start then right click on my computer then click Manage
Once the window comes up click Device manager
Click the + to open up the Display Adapters and then
Right click on your graphics chip set and click properties
Once the properties window comes up, click the Drivers tab
And click Roll Back Driver and then click Yes
Another option would be download different or updated Drivers