I completely understand where you are coming from, and I know how tough it can be to put yourself out there, but you need to put think from the perspective of your coworkers. If you are quiet and do not engage in conversation, they probably won't either. Again, I know its really hard and I have been in the same position as you, but its important to at least try! Set goals for yourself (i.e. try to make a conversation with one coworker a day). Eventually it will get easier. Hope that helps. Let me know how it goes!