dragon quest monster; joker

im stuck in the sun and moon temple, i collected the sun blessing but the mirror says i need the moon but i cant get to the moon one because all the doors are down can anyone help please iv been stuck there soo long and its really annoying

Go and talk to that Commissoner Snap or something, you will battle him and the brigde on the Infarn Isle will open. Now you can reach the north side of the Isle which has the sun and moon temple.

I get to the north side just like i told you but i'm stuck there. I get in the moon temple .Press the blue button, then the door open, then i don't know what to do next

i am having the same problem. moonstone seems to be impossible to get