It's not about your looks lar.

Trust me. Guys (or the rather shallow ones, at least) may prefer to flirt and hit only on girls who are pretty, with no interest for the rest regardless of personality.

But if you're an interesting conversationalist, or you connect well with them, they will still TALK with you even if you look like frankenstein or the incredible hulk, even if they are not interested in you.

The problem here really isn't your looks. You're either unlucky to be surrounded by people whom you cannot connect with, or it's in the way you converse and your personality. Personally, I feel there's nothing wrong with NOT being the centre of attention and conversation. But since you actually want to, I'd suggest you look into those things instead of thinking that guys don't want to talk to you because you're not pretty.