How to reset quest progress

I'm stuck outside of the vent from The Envoy part 1 and can't enter it anymore because the npc is gone. I went back and talked to the first npc but it wouldn't let me restart.

 

i dont think u can reset quests but you can /class or other things to try make the npc spawn

 

thanks, I tried but the problem is that the npc opens the door in the screenshot, so they don't spawn with /class