If you have refunded him without getting the item back, you can't do anything through Ebay.
You must read the Money Back Guarantee as it outlines the process for sellers as well as buyers.
If a buyer messages you about an item (and you were clearly in the wrong here) apologise but insist they start a return case through Ebay.
Then, provide a return label through the case.
Then refund the buyer when you get your item back.
If the buyer refuses to return the record, apart from messaging them, there is not much you can do.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)