I was in your situation, but not because no one liked me, it's because I was stuck on one girl who didn't feel the same way about me for a lot of the time.
All I can say is...no shock here...be yourself. Don't try to act anything out, people can tell. If you think you may like a guy, start hanging around with him if you feel comfortable doing so. Start paying more attention to him, and if you two become good friends, maybe start flirting with him. If you ever go somewhere, like the movies, with friends, try to sit by him so you two can talk when possible. Nothing is worse in getting a guy/girl than not being able to talk to them, then how will you get to know him or her?
Hope that helps a little bit...
Coming from a guy, that's what usually happens to me.
It's okay to not have had a bf for awhile or at all. It's normal and lots of people are in the same suituation. Relationships will happen when you least expect it. In the mean-time, talk to people, go out to places you like, and be yourself. You'll meet someone soon i'm sure.
belive it or not, for quite a few guys (the ones i have talked to), a great personality is all that counts. it doesnt matter if you are pretty or ugly (i bet you are pretty though), be nice to a guy and he will probably like you. could take some time, but it should work eventually. good luck.
Maybe some of the guys think you are already taken, or the ones most interested in you are too shy. Think about which boy or boys interest you and try to start a conversation with him/them. You can casually mention that you don't have a bf, or that you are tired of being home each weekend stuck with your parents, or something, to prompt them to consider asking you out. Or, if you are sure the boy is shy and does not have a gf, go on and ask him out. I was terribly shy and would have loved for a girl to have asked me out. Actually, one did, and while we didn't hit it off and only had the one date, I loved it.