Uh stuck in the Panarii temple in Caladon

So I was in the sewers in Caladon when I saw a passage and when though it to the Panarii temple and so then there were some stairs I went up, but uh now I'm stuck and can't get back down to get out. I'm in the room with the coffin and I can go up another staircase but that leads to a magically locked door. Is there a way to get back down or do I have to go back to a past save file?

 

The cornerstone in the top right corner should light when your mouse goes over it. Now, I'm saying right in respect to the character's viewpoint when you walk towards the coffin.

Here's a picture;

 

Thank you so much.