This is a thru-axle, isn't it?

If the far end can be seen then have someone take something that can fit through the hole of the bike frame and push on the thru-axle while you turn the other side with a hex key or what ever is appropriate.

Or is it the hex socket that is stripped? If so, maybe the quickest way would be to jam a torx bit in it or just get some epoxy resin or epoxy glue and glue the hex key in.