This is for the PC version.

I am wondering if you show up and your hunter NPC's are dead, and Sinding is no longer in the area, is there any way to fix this?

I have met him outside traveling near Whiterun, and have decided what to do, and now the quest is just stuck where it is at, Sinding is nowhere to be seen, and the marker is no longer active, is there somewhere he goes to randomly? Or perhaps some sort of console command to move past that part of the quest?