Undo Deleted Records
That's called a Major Whoopsie.

Assuming you didn't use transactions around the delete you are stuck with scanning the log files and redoing all the INSERT and UPDATE queries. If you don't have a query log then it's manual entry time.

If it's any consolation the Government of Alaska had a similar issue a while ago, further compounded by the backup tapes not being readable. You've probably lost a morning, they lost the whole thing.