I have a question that is probably and easy fix but I have no idea. Plz help, thanks!

I recently did a full system recovery on my pc. Before I did the system recovery, I could set my screen resolution to 1024x768 Now, after completing the system recovery, I can't go past 800x600. When I try to set it higher my monitor goes black (which I know it is supposed to do) but the picture never returns. I have to reboot and start windows with VGA mode and put the resolution back to 800x600. Any ideas as to what happened or how I can fix it to where I can go back to 1024x768? Thank you very much in advance!!