I'm not sure what religion you are, or if you follow one at all, but this worked for me. I'm a regular Voodoo practitioner. Beginner, but still a practicing one. Just like Christians believe in God as the Father Almighty, I believe in Papa Legba like that. He's a bit of a trickster, so whenever I would lose items I would tell him to give the item back and in exchange do an offering. I lost my cat last week and I prayed to Papa Legba to bring him back, 10 minutes later I found him crying and scared in a thorn bush where he had never been when he would run out before. Basically, if you have a "spirit" or "god" that you pray to, that's one suggestion. In terms of spells, try chanting this:
Keeper of what disappears,
Hear me now -- open your ears.
Find for me what I now seek,
By Moon, Sun, Earth, Air, Fire and Sea.
I said this when I lost my Tiger's eye bracelt and the next day I found it.