I am trying to complete the quest "Madresi Dran and the Wandering Dead." I went through the angarvunde catacombs door fine, but when I try to go through the angarvunde ruins door it says it requires a key. the key no longer shows up in my inventory either.

I don't know how to finish this quest! Please help.

Also, I cannot go back to a save point before starting the quest because I had started it a long time ago, stopped for some reason (could be this dang door) and came back to it just now.

Any help would be appreciated. Thanks.