Problem with a transaction for refund

[sashko_11-7]

Hi,  I have a problem with a refund which I had to do because I found an mulfunction in the product before I ship it. I have incorrectly reported to eBay that the buyer wants to cancel the transaction and tried to issue a refund via eBay. eBay then sent me a message that cancellation is not successful and I have to issue a refund. Now they wait for the buyer to confirm receipt of the refund to close the case. However,  I'm not able to issue a refund via eBay - the transaction does not appear in the Resolution center , although the buyer paid via PayPal through eBay. I no longer see the money in my PayPal balance either  and the buyer later filed a claim via PayPal, so now I'm not sure where the money is.

I simply want to return the money to the buyer but I'm not experienced with issuing refunds and may have done something wrong. Please advise me how I can fix this - is it PayPal that keeps the money or eBay?