Quest bug(R.o.L 3)

Sorry to ask but my quest have a little bit problem without a solution
When I have to explore the castle (Stage 9), I died.
When i go back again, i continue it until the talk between Lari and Dullahan.
I found that there is a mistake of the effect, so i go to the class selection and continue it
However, it bugged and I was stucked in the place that they have a talk
When I go back to the castle, the system noticed me there's is no point in going through here anymore.
I have checked the youtube video and the person will have a opened door in (-3474 36 -10635)
But my door is closed
Is there any solution or i have to restart the quest, or even playing a new account??
plz help ;w;