It's frustratingly difficult to help when you don't give any factual information. To ask the obvious, was this a business seller or a private seller? What was their returns policy in the listing?
If you buy from private sellers it isn't like the shops. Private sellers don't have to accept returns when selling their own, unwanted possessions. If the listing stated that they don't accept returns you accepted this condition when you bid.
If they're a UK business seller your statutory consumer rights apply and they ARE required to accept returns, for any reason. If you opened a return request and the seller accepted returns, it should not have been closed - in fact, it could have been treated as a money back guarantee case.
You could try asking again in the morning, and giving us more information.
