Before resorting to the walkthrough, here are a few useful hints that might help:
-Remember the hint babes. They have a hint for every item in the game, even the ones used for the endings that don't have a linked hint babe.
-Not all endings involve getting a boy in the castle. There are a total of two endings that don't include wooing a boy.
-The courtyard is viewable from the upper level (that area straight to the right of where you start the game).
-If you only have one ending left, you might want to check out the character bios section of the bonus menu. Characters will not appear in there unless you have their ending or they have no ending to get.
If none of those helped you or you just want to see an ending, you can check out the walkthrough section on our main site here. I apologize for linking off site, but with the non-linearity of the game, it was easier to organize this way.