If you didn't list the item that is up for sale on your account then end the listing now.
Cancel any sales on the account and you will be prompted to refund if any paid.
Message the buyers and apologise explaining you have been hacked and you didn't put anything up for sale.
Clear cookies and temp internet files on your computer, clear browser history on all browsers you use then restart computer.
Change your password to eBay accounts, PayPal, and email addresses. Do a virus scan as well.
If anyone leaves feedback contact eBay to have it removed.
Call PayPal to explain and have them credit any fees back.
