How can I connect with people?

I don't know exactly what's wrong with me. I'm 17 and I feel so damn lonely! Ha ha, It's really just miserable sometimes. I have a lot of friends, and girls seem to like me, but for some reason I have trouble connecting to anybody, or getting close to people. Some days, I avoid contact with my friends and girls because I don't feel like I'm up to conversing with them. I don't know why this is. I realize I may be isolating myself--but how can I stop?How can I connect with people?
Perhaps you are just bored or not interested with the people you see everyday. Try going out to different places you have never gone to before or would regularly go to and see if you connect with different kind of people.