eBay

I SOLD A WATCH, IT WAS AUTHENTICATED AND SENT TO BUYER. NOW THEY WANT TO SEND IT BACK TO ME BUT EBAY SAYS IT WILL GO BACK TO GET AUTHENTICATED AGAIN TO MAKE SURE BUYER DIDN'T DO ANYTHING TO IT. WILL I HAVE TO PAY TO GET IT AUTHENTICATED BACK TO ME?? ...

I have a crazy buyer that says she has returned a package but she won't give me a tracking number for it. Is there a way to find out if she even really shipped it?