Open iTunes on your computer.
Let the full music library load.
Click on "Edit" in the top menu bar.
Click on "Undo Delete..." where the ellipsis represents your playlist name. This should restore the deleted playlist, even if it was not the last file you deleted.
Open iTunes on your computer.
Insert your backup disc into your computer's disc drive.
The iTunes program will ask you if you want to restore from the disc. Click on "Restore." Assuming you backed the playlist up on this disc, the program will restore it.