Assuming it was sent using eBay's Simple Delivery (as your other items are) in theory you are covered and ebay should refund the buyer, not you.
eBay say:
You'll be protected if the item is lost or damaged from the point the item is scanned into the carrier's delivery network and until it's marked as delivered.
Contact ebay and ask them how they will be refunding the buyer. You can use callback on here:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Please let us know how you get on.