Try this. Go into your quest log, and click a quest for the world you are currently in. Finish it. Go to the guy who gave you it and get your reward. If he has another quest and you get it automatically and you can't decline it that means its your main quest. if none of your quest is your main quest then you lost your quest. to solve this. Go into the world you are in. and keep doing quest finder in till you find your main quest. hope this helped!