How long is "a few months"?
You have 30 days after delivery to open a Not As Described dispute with the seller and get a refund through the eBay Resolution Centre which is at the bottom of this page and most eBay pages.
The first suggestion (not a demand) is that you contact the Seller.
But all you want from him is your refund, which takes seconds to process.
He is allowed to demand the return of the item, but if the reason is Not As Described, HE pays for the tracked return.
When tracking shows it returned, you are refunded.
That door is now closed.
BUT
If you paid by Paypal, you have 180 days (six months) from Payment to open a Not As Described dispute with PP.
The PP Resolution Centre is at the top of most PP pages under Tools.
Same process, but PP requires you to pay for tracked return shipping.
IF you kept the tracking number on your return, open a Paypal Dispute, give the tracking number in the Dispute to show return delivery (again, delivery not shipping) and you will be refunded.
BUT
If you did not keep the tracking number or did not track (which is expensive internationally), PP cannot help you.
If you back your PP account with a credit card, you could try phoning the 1-800 number on the back of the card and asking customer service about a chargeback. Card policies differ.
BTW, if the seller does not refund you promptly and voluntarily, eBay or Paypal will, and then go after him for their money. They have his financial information too.
He would also get a Defect on his selling account which leads to higher fees, restrictions on the number and value of listings, and possibly a closed account.
