I lost mine too. I just found a bolt and nut and washer to replace it. Works fine.
Oops. Reread your post. You need the thing it latches onto. Did the screws that hold the latch on come out and are gone? That latch would snap on to a couple of screw heads that are backed out enough to give the latch something to hold. You'll have to lengthen the latch bolt to it's maximum length though.