I think it's important to remember that life does happen. But maybe talk to a mod about when it would be a good time to try to sell the piece again if the person doesn't come back soon.
Back when i played another game, i had someone do work for me on it, during their work, my job came to an end and i didnt have a home computer, so i couldnt get on to pay them or communicate... Years went by and i would still think of that person and feel awful about it. I recently finally got a home computer and made contact with them. That game has died now, but i still sent them compensation and apologised. I was horrified.