sorry mate, if you peeled it of the inside of the case so it could get lost theres little microsoft or anyone can do. You would have to send them the disk so they could work out which game it is an check its legallity. And i doubt microsoft has the time to do that.
Buy a new copy of the game if you really want to play it.
Out Reach
The guy who writes the erotic fan fiction in Yeebaagoon's signature