You can only ROLLBACK data if you performed the delete in a transaction and have not committed the transaction.
If your database is in FULL or BULK-LOGGED recovery mode, you have a few recovery options.
1- If there is no danger of data loss (i.e., no rows have been updated since the delete), you could backup the log and restore the database to a point-in-time prior to the delete.
2- You can back up the transaction log, restore the database as another database to a point-in-time prior to the delete, and then compare the tables to find the records that have been deleted.
3- You could buy software such as Lumigent Log Explorer that can identify transactions and generate recovery scripts.
If the database is in SIMPLE recovery mode and you have a recent full backup, you may be able to restore that backup as another database and compare the tables to identify the deleted rows. This will not work if the rows were inserted or updated since the last backup.
Terry L. Broadbent - DBA
"The most likely way for the world to be destroyed, most experts agree, is by accident. That's where we come in; we're computer professionals. We cause accidents. (Nathaniel Borenstein)