How do I restore my computer to what I had a couple hours ago
I screwed up with an application I needed on my desktop and need to restore my computer back to an earlier time. How do I do that?
MacBook Air (13-inch Mid 2012)
Well, you have not told us anything about what backups you have, or what backup method(s) you are using.
If you have no backups, then you cannot restore anything.
If you use Time Machine as your backup method, then see "Restore Everything" from the "Restore" section here:
Use Time Machine to back up or restore your Mac - Apple Support