So I was trying to play a game, and when I launched it, my monitor would say it's out of range. So I tried different resolutions for my monitor to see if it would work. I tried 800x600, and now my moniter says out of range all the time, even when I'm at desktop. And now I can't see the screen to change it. How to I go back to my native 1920x1080?

Fixed it by starting up in low resolution mode and switching back to native from there. Doesn't make sense but whatever.

what game?

The Cat Lady. I posted a topic on the Cat Lady sections about how to fix that issue.