If you get stuck check out if you have achieved following things.
Have you blocked the sandstorm?
Have you looked at the lamp in the museum?
Did you talk to the genie ? and ask how to get him home? Did you take a spirit quest after that?
In front of room 3
Stick the cosmic stamps into the lamp. Did you find Otto after that? ?Make him lose all three wishes.
He is in room 3. Look into the window.