Uh oh. That's a new one! D-: I'm so sorry! Are you playing on the Mac version? That one tends to be buggier. When you defeat Brandy, there should be a star icon in the bottom right corner of the bathroom entrance. If you click on it, it should let you go to homeroom. Did that star icon show up? If not, I'd maybe try restarting it? If you hold down the mouse button, it should let you skip through the dialogue and you should be able to get back there really quickly.