Returned item not returned

[techcharger]

I sold a item on eBay, however the buyer did not like it so he put in a request to return. He shipped the item and added the tracking number however due to address query (not sure what address the buyer put) it was sent back to him. He has now won the case with eBay saying he sent the item back and the tracking shows it was delivered. However tracking does not show that, instead shows sent back to buyer and I am now out £180. What do I do? 
I have messaged the buyer several times but no response. 
I dint understand how the investigation processes work. 

[tressygirl]

Contact eBay Customer Services,  appeal the decision for the refund,  giving a full account of what has happened.

No guarantees here,  but you need to tell eBay as they do not know about this outcome.

Contact them this way.

https://www.ebay.co.uk/help/contact_us?id=4814&st=10

The contact links can be found on the left on that page.

Lines open today between 9 a.m. and 6 p.m.