How can i get my thousand dollars back!!!?

I got a money order to pay my rent a day or so before feb 1 !! I do this same routine every month i pay all my bills by money order and send by mail but this month my rent check never made it to its destination!! And i sent the jacket i wore to dry cleaners and the stubs from money orders were in pocket of jacket!! What do i do ?? Its a thousand dollars i dont have to just throw away