Sometimes changing a computer's screen resolution to an incompatible setting can cause the screen to turn off. This resolution setting is saved, so simply restarting will not fix the problem. To resolve it, one must start the computer in Safe Mode. This allows changing the resolution to a compatible setting. Specifically, one should press F5 or F8 during startup, select Low-Resolution mode or VGA mode depending on the OS, change the resolution, and restart normally which should restore full functionality.

1. Sometimes when you are changing your screen resolution for your computer. If you choose a resolution
that is not compatible with your Graphic Card your computer screen will turn off and you won’t be able
to use your computer. Even if you restart your computer it won’t make any difference because these
setting will be saved. One way to fix this problem is to use Safe Mode. So in this tutorial we are going to
explain step by step how to fix the resolution problem in your computer.
Step 1:
Hold the power button on your computer to turn off your computer.
Turn on your computer again. Once you turn on your computer keep pressing F5 or F8 button to Enter
Safe Mode. The safe mode window looks like this in the following window.
If you are using Windows 7, choose Enable Low-resolution video
If you are using Windows XP to fix the resolution problem we have to use “Enable VGA mode .

2. Step 2:
After you press “Enter” wait for the Windows to start up. Enable Low-resolution video mode looks the
same as when you start your computer normally there no difference.
If you are using windows 7 you change the resolutions by clicking the right button of mouse then
“Screen resolutions”.

3. After that select a resolution that you think its compatible with your VGA
After you are done changing resolutions, restart the computer and start the computer normally and you
should be able to work on your computer as before.
If you change the resolution and the same occurs again, then uninstall the graphic card drivers and that
should fix your problem. After that reinstall the graphic card drivers again.