Unless the player has made it clear he was trying to kill his character permanently, definitely have him send up somewhere that he can be rescued or otherwise reunite with the rest of the party after a reasonable amount of time.
I'm partial to githyanki answers. I'd go find a copy of Fedifensor from Dragon Magazine and have him show up in the ruins of that castle. Just after seeing it mostly in ruins and maybe that there's some hostile monsters that have taken up residence inside, he looks out and sees a spelljamming vessel approaching ... and that's where you end the session.
Next session, see if the other players figure out a way to go after him, in which case, they can be on that vessel (or the vessel after that one, as the original is full of trouble of some sort that they will need to arrive and rescue the fighter from).
Alternately, if the other players are stumped, when you switch back to the fighter, it's someone friendly or neutral stopping by his desert island and he can start the work of getting home, with a few short side adventures on the way.