Maybe "he" (the guy you like) doesn't go for your type. Try another guy; there's more than one. I know it's disappointing when the one you like doesn't like you back, but that's something we all have to adjust to. Look around; see who else is there.
If he doesn't like you for who you are, then it just wasn't meant to be. You should find a guy who loves you for who you are, and not try to be someone you think he will like. Good guys like good girls.