By ' gone' do you mean they are not answering your messages?
Was it the TV / LG ? That sold 8 days ago so it' a reasonable time to keep the item but no longer.
Send the buyer a polite message asking them to please confirm a viable collection date by *** day if not, you'll deem the item to be unwanted and will be refunding them.
If this happens cancel the order citing Buyer Requests to Cancel. This fully refunds them and your seller performance is not affected.
I would consider blocking this person too, so they do not return and mess you about.
https://www.ebay.co.uk/bmgt/BuyerBlock?
@kateryna_2005