Per eBay's Money Back Guarantee for buyers, once an item is late by at least one day, but les than 30 days, the buyer can open an item not received case with eBay.
All the buyer needs to do is: find the item in your Purchase History. Click on it. In the drop-down menu, click on "Item not received". Unless there's tracking (and you state there's not) the buyer has 4 days to refund you. If that doesn't happen, eBay will do it for him.
What do you mean when you say that there is not a seller listed?
Care to share the item #?
