Aww, I know how you feel. I hate that too, it has happened to me.
Our Internet is connected to my dad's work, and he has the username and password already in. But one day the password had accidently got erased, and he can't remember it. So I wasn't able to go on the Internet until he asked his work again for the password. It was really annoying.
and also, I forgot my password to a few different sites too, but at least they're not that important.