I have played Warcraft 2 and Diablo in a full screen format with bars around the screen, now my game screen is small in the left hand upper part of screen, I'm not sure how to restore it.

Dell Laptop with windows 10, Thanks for any help

Alt gr + Enter should restore it.

yeah it's because you have a wrong resolution, something like that. I had that problem aswell, and fixed it by changing the resolution to the one that fits my monitor.