HELP!! quest stuck or key lost, Ice barrows dungeon

So I've been trying for the past few days asking in chat and looking at tutorials online on how to find the ice barrows key guardian and i cant find it. When I talk to the NPC that gives you the quest to enter it tells me "It will be dangerous, perhaps your toughest fight yet...but it must be done. If you need time to prepare, do so. But you must end Theoriek's pain." which im pretty sure is the end of the quest line however I did this months ago and have managed to lose the key. Is there any way I can get into the dungeon or am I boned?

 

You can get keys from Ice Barrows Key Guardians, the trade market, and world events near the dungeon's level. Dungeons are meant to be repeatable content.

 

just to add on, dungeon key guardians usually spawn around the area that the dungeon usually is. so for ice barrows, the key guardian tends to spawn around the nesaak area