Be honest and up-front with your co-workers. Let them know that you're having a problem. If you don't feel you can talk to the group, select one person to talk to. Or talk to your boss.
You can simply try to talk with your coworkers everyday. Try acting interested in their home life and home activities. Try to contribute to the canversation and offer help if need be.
Food! Food is always helpful in bringing people together in the office. People feel a lot more comfortable if they know everyone is doing the same thing.
It might of helped when you started to people friendly and cordial with collagues. Good advice would be to just be friendly and not sometimeish with people. Also don't be too frieendly with people who are not noticeably not friendly to you.
