Was it a return for change of mind as the option to add tracking should be on the return.
If you cant add it too the case then you would have to contact ebay and ask them to do it
as it needs to be on to prove Delivered or attempted delivery
To contact ebay at the top of the page under Seller help the item may come up for you to add or deal with the problem or you scroll down for contact details of Call me back of chat with us
