So I was working on the main storyline in Zuldazar and I must have abandoned the quests at some point and when I went to go pick them up for the quest giver they are no longer there.
I was working on “The Throne of Zuldazar.” now I have nothing in that area for the main storyline but I also don’t have the achievement.
I’d suggest the following:
Check Wowhead for the name of the quest and read the comments to see if anyone else has had a similar issue.
If that doesn’t help, post on one of the support forum, particularly Customer Support. See if they can help.
If not, put in a ticket, explain you appear to have deleted a quest and can’t figure out how to get it again. I’ve done that once or twice and the GM who responded has reset it for me.
I’d also check to make sure your memory isn’t playing tricks on you, and you did some or part of it and have just forgotten. It happens, trust me.
Good luck.