If you bought from a business seller, they would have to accept a return.
Did you open a return case through Ebay or did you just message the seller?
If you opened a case and then returned using a tracked method, the seller should have refunded within 48 hours of the tracking showing delivery.
If they don't refund, you have to go back to the case and ask Ebay to step in. If you don't do anything, after 21 days the case closes.
So, did you follow the proper process?
It looks as if either you did not open a case or you let the case time out and you have lost your money.
"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)