Overcome such fears need as well as all phobias - go openly to meet his "enemy". If you are afraid to communicate with colleagues - communicate with them as often as possible, initiate a conversation, ask for help or advice. If you are fairly closed, first try to make contact with one of the employees on the phone or by email. Once you have communicated virtually proceed to real communication - contact with a minor request, tie a conversation on a specific topic without fear of what you absolutely incompetent in this matter. When people ask for help, they tend to react calmly to it and sometimes there are happy to share their experiences and give something. Having established the first contact, proceed to the next stage - try to participate in the conversation. Join the debate to try to express their opinions.
If you experience tightness, stiffness, sometimes passing into a real panic when you have to speak in front of colleagues, for example, at a meeting or at a professional training, then this fear will have to fight frequent performances. Prepare in advance at home, play possible situations better in the mirror. During his report to colleagues find people whose opinion is the most welcoming and friendly, and mentally refer to them, imagine as if you speak only in front of them.
Fight the fear of communication at work need only empirically, accumulating a daily experience.