XBOX parent approval

I've got some trouble with the xbox login. When I try to log in (in the music app or something, or games) then it says I need to agree with the new User Agreement. OK, not too difficult, I thought.

When I get to the XBOX site to approve the agreement it says I need to log in with my parents account, which I forgot.. So I don't know what account I need to use. Do you guys know a way to know what your parent account is? There is nowhere I can find it, maby you guys can help me!

Thanks in advance.