FOR GODS SAKE SOMEONE HELP!

when i was young i stole something from someone and i recently found it in an old box. i want to return it because i feel really guilty about taking it. i've been out of contact with this person for a few years but we are still friends on facebook. i'm thinking of returning it anonymously through the mail because the thing i stole can fit into an envelope without problems. or is returning it face to face better. how should i go about doing this?