assigning a user to a listing

Hi, a new user added a listing to my site. I added a new category to suit the listing and then edited the listing by ticking the new category in the edit listing section. The listing has been now assigned to me. Why? How can I reassign the listing back to the guy who added it in the first place? I’ve gone in to edit listing but he does not come up in the author box? I’m running the classified theme url is http://www.localgardenertrade.org Site unusable if I can’t edit listings