anyone know how to unblock someone from snapchat?

And if they're not in that Blocked list at all, you never blocked them. Either they blocked you or they deleted the account. Nothing you can undo from your side then.

Profile, then the gear icon, scroll to Privacy Controls and tap Blocked. Hit the X next to their name. The thing that catches people: unblocking doesn't make you friends again. You'll need to search for them and add them back, and they have to accept.