I would talk to the parents of that boy, and if they argue or deny, talk to the boy yourself. Talkto your daughter and make sure she understands it wasn't her fault, and that no one is supposed to touch her. Tell her to yell "no'! if anyone tries to touch her. Who takes care of your daughter when you go to work? Make sure they know what happened and that they keep an eye on that boy. I assume you discussed it with your roommate's parent(s). Sadly, we have to teach our children at a young age, what is not appropriate.