Run a Scan job to find out what sessions are on the tape.
Manager > Quick Start > Utilities > Media Assure & Scan
If you want to restore the whole session then Quick Start > Restore > select Restore By Backup Media > select the specific session # to restore and the destination.
If you want to do a selective restore then Quick Start > Utilities > Merge > and select the specific session #.
After that back to Restore and select Restore by Session, select the tape, session #, and specific data needed.