That usually means the seller's account has been suspended by ebay.   In any case you can only open a return case through ebay within 30 days of the delivery date.   Assuming the seller won't volunteer a refund your other option is, if it's still within 120 days of payment, to contact your payment provider and see if they can help.   After that time, if the seller is in the UK,  you're looking at using moneyclaim online (small claims court).