You like a boy at school but you don't know how to talk to him?

You could talk to a friend of his and ask about him. Or you could leave him a note somewhere you know he'll find it. You could also hang around him and his friends. The truth is: he's just a boy, and you can talk to him like you can talk to anyone else. If you can't find the Words when you're around him you can practice some lines in front of the mirror to gain confidence. That way when you lose your tongue again you can fall back to the stuff you've practiced on and it won't be embarassing for you. :)