It may not be appearing in your eBay account, because you may have made the purchase as a Guest Purchase, and here, your eBay account is not used.
You cannot pursue any refund from eBay as they have a 30 day MBG policy. However, from the link below you can retrieve details of your order if made as a guest purchase, then only if the seller is a UK registered business who offered a 12 month guarantee, is it worth pursuing with that seller.
The best option is to get a new confirmation email using this link - https://www.ebay.co.uk/help/guest-order?topicId=4065&af=2.
From there you will be able to select the view order details to find your seller.
Orr, try your payment provider for help with a refund you may just be in time to claim there.
@brou22649