Hi,
Thought this is up for everyone to answer, not only "Mr Ashish". If I am not wrong the buyer has registered item not received case, please go to your resolution centre their click on take action in front of this case, and write buyer a message saying that the item has been delivered. give him Proof of dispatch, ( scanned copy of bill) and try to arrange for POD , Proof of delivery from your courier service, ask them to get it scanned from the delivery office and mailed.
It happened same with me buyer claimed refund after the item was delivered to him, It like they are experimenting with the claim refund thing hoping they get their money back.
I see that you have none listings live,, has eBay pulled them off??? In that case I would suggest you to send a mail to incswebhelp@ebay.com and inrswebhelp@ebay.com with proof of delivery and dispatch..
let me know the progress! Good Luck