What can I do?

I honestly don't know how I'm going to get through this year. Last year. My concentration levels have already deteriorated to practically nothing, I'm stressed over things I shouldn't be thinking about... I really wanted to cry in class because I don't even know what I'm doing anymore. I can barely talk to my friends anymore, it seems like too much effort when no one would really listen... I must have missed out on heaps during the time I spent working, I feel as if everyone grew closer and I'm further apart than ever. Or I guess maybe it's just me, my inability to fully trust anyone and have a close friendship. Why the hell did I turn out like this? I hate it when I start hating life, I hate it when I feel so disconnected from everyone and everything... Why can't I just be happy? Life is starting to repeat itself, almost like the time in Yr12 when I felt so empty. I really want to travel. Wouldn't it be nice to leave everything behind and start anew?

-Edit-
Maybe I'm being a bit melodramatic. I can't really tell. But I hope these lingering thoughts will leave me soon so I can get on with my life.