Attempted delivery counts for delivery in eBay's eyes, so should the buyer opens a case now for, item not received, entering those tracking numbers into the case details will close the case in your favour. Should you then receive this item , morally I feel you should refund, but this will be outside eBay as the case is closed.
' Item on way back to seller. '
If you do receive it, cancel the order citing Problem with Buyer's Address, this fully refunds the buyer and doesn't affect your seller performance.
Up to you then if you wish to relist it again , for the buyer to buy, and pay you again through eBay checkout. You can then message them the item is relisted for sale.
@sp_166