There is no way to process this through Ebay.
They allow you 30 days to start a return using the Ebay Money Back Guarantee.
It is likely that the seller knows this - you will have to liaise with the seller to arrange a refund.
For example, they could send you a cheque or make a payment into your bank account.
"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)