Uh-oh, I think I deleted something on my computer that may have been important

I downloaded a video editor to convert my videos, and it wasn't any good so I went to delete it, and I thought that's what I deleted.

My computer restarted without asking me and when it came back it only has 16 colors(that won't change) and also it's on a small monitor setting that also won't change.

Any help would be appreciated

Thanks