Re: Rape if drunk?
If he did have intercourse without protection she would most likely have had semen residue on her public hairs, underwear (if it was put back on) or bed sheets. Under US law it is rape, though it might be near impossible to prosecute over there given the lack of concrete evidence.
Sadly, if it did occur but she doesn't remmeber, it might be best to stop talking about it. No use telling her she is a victim if she doesn't feel like one, especially when there is probably nothing she can do about it, other than learn from the experience. If you see the boy again, you can certainly give him a piece of your mind and state you are asking around about him and if you can find others who he did this to, you will go to the police.