How do you know he likes you if you tell him you like him and your best friend said he did and i always trust her and never lies and his friends that are girls tell he does not like you is it not true?

Don't mess around, just ask him yourself. Boys appreciate it when girls do not complicate things. It might be hard to ask him, but if you really want to know, you need to find the courage. It doesn't have to be a big deal, either. Just say something casual, like "So my friend thinks you like me. Is she right?"