It's a fact of life that no matter who you are or what you do, not everybody's going to like you.  I think that's especially hard to wrap your mind around when you're younger.  It sucks not being liked and it's mystifying when people seem to dislike you for no reason.  It's not uncommon to conclude that you're doing something wrong and to attempt to change yourself to fit in more so hopefully everybody will like you.  But you're never ever going to get everyone to like you.  So really, the best possible thing you can do is like yourself.  Be somebody that you like and do things that you enjoy and are interested in.  If some people aren't going to like you anyway, you may as well have it be the "right" people not liking you, i.e. people who don't share your interests and you don't have anything in common with anyway.  Or who just suck themselves.  Why would you want to be liked by sucky people?    

On that note if someone doesn't like you, screw 'em anyway, right?  Why waste a lot of time and effort getting someone to like you when chances are you wouldn't like them anyway?  

I will say as a caveat, if you seem to be repelling everyone you meet you might want to examine your own behavior and make sure you're actually not being a total piece of garbage.  But of you're honestly doing your best to be a decent human, then more power to you.  The person it's most important to be liked by is you.  

All right, I'll be holding self-help seminars across the nation this fall.  That is, if anyone wants to book me for them.  Anyone?  Anyone?  Bueller?  Bueller?