The Missing Diplomat Pt. 11

The NPC named Mikhail in the Menethil Harbor for the quest called The Missing Diplomat bugged out. I failed on doing that when I accepted it for the first time since I failed to kill Tapoke "Slim" Jahn. So I abandoned the quest so I could get it again. But sadly, the NPC where I can get the quest bugged out and does not give me the quest anymore. The quest indicator on its head disappeared. Now I cannot complete the chain quest. I am in part 11 on this 17 part chain quest. Any suggestions on what to do next? Thanks!