go to your home page of Listia and under my activity look for something that says "My open auctions". CLick on the ring auction and then as soon as it opens there should be a red X on the right had side right next to were it says EDIT
Crap! Best thing for you to do is make a comment or updat sayig that the item is lost so stop bidding and that the wnner will be immediately refunded teir credits at the close of the auction. Otherwise, I dont know what to tell you hun. I guess they only let you edit or cancel your auction so close to the ending date. Could contact Listia too but they take a long time to get back to you.