Items that are not shipped back after return request
I do not use FBA and ship all my products myself. A customer ordered an item 74 days ago and they had a return request approved 65 days ago. They have not shipped the item back since then, and I was wondering if they were to finally ship the item back, would I have to refund the customer? Also, is there a certain time period after which if the customer does ship the product back, I am not liable to refund? Thanks!