If you can still access the original listing (always possible in my experience) then on the right side of the listing page you will see "Seller information" and just below that is "Contact seller" - click on that and you get a panel with choices on what to raise. If you choose "Other" you can write a short message and for example offer to buy or ask if the item will be relisted - you simply send that off (remember to tick the box for a copy to yourself).