If you started a return request within 30 days of delivery you will be able to escalate it to ebay after 3 complete working days.   So when that time has passed go to the return case, click on Case Details > Respond to Case > Escalate This Case > Submit.

What you have told us could have two meanings.

Did you mean that delivery of an item you ordered was attempted, but was returned to the sender because for some reason it could not be delivered, or you refused to accept it?

Or that you have returned an item item that you no longer want, or was faulty? If so, did you follow eBay's procedures for returns and refunds?

It's not clear, have you opened a case for the return?

Hopefully you have, then,  enter the tracking numbers into case details. 

On receipt of their item,  it gives the seller 48 hours to refund you.  If they don't,  you need to escalate the case,  eBay step in and force the refund.

The above is the correct procedure to receive a refund, if you have not followed this, no message to eBay or the seller can enforce a refund.

@melfa_8091