I will assume you are running the GOG version in Windows (which runs in DOSBox). Resolution has nothing to do with your issue, but it would be too long to explain.
Try pressing ALT+Enter. This will toggle the game between full screen and windowed. It is not clear from what you wrote what is the current status, so you will need to do this once if it is in a window now, or twice if the game is fullscreen.
If that doesn't work to restore graphics, and your issue is that you don't want to lose progress, press ALT+S to quick save. Try ALT+L to quick load so that you know your progress was saved properly, and then close the game with CTRL+F9 (this ends DOSBox immediately).
Enter the game again normally, and everything should be fine. The save game corresponding to your quick save is in slot zero; the top one in the list when you choose Load Game from the blackboard menu.
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You also have the autosave slot in number eight, which is used every month, so you will not lose too much progress even if you fail to save now.
I did alt enter after which the resolution problem started. Every time I start the game, the right side of the screen is to the far left, and the rest of the screen is black. I'm trying to get it back to fill the whole screen, but repeatedly pressing alt enter changes between full screen and window, but doesn't fix the fact I can't see the game in full screen. Just the right side of the game on the left of my computer monitor and the rest of the screen is black.