If you have backup, then restore it. In order to restore to a point in time, you'll also need the transaction log backup that contains this data plus the entire transaction log chain since the last full backup. If you don't have these, then you'll need to purchase a third party tool such as Lumigent's Log Explorer to read the transaction log.
If you don't have a good backup solution in place, now is the time to start.
Also, you posted your question in the data corruption forum. Your problem is not with corrupted data but rather user error.
The easiest thing to do would be to restore from the database backups to a new database, and then apply the transaction log backups up to the desired point in time. Then copy the data you need from the new database to the old one.
One extra possibility is that you have a Full Backup and your database is using a Recovery Model of FULL. In that case you could now take a transaction backup, and then restore Full + Transaction backups in the way that Tara and MVJ describe