My research work stolen and published as his own by the co-author without my consent My research paper was stolen by the co-author and published as his own. What do I do? All the  data the paper is based on is my own work. I got it accepted in another journal but now I cannot get it published according to the copyright terms and conditions.
Let me echo scaaahu's excellent advice: Calm down.  Obviously you're scared, and with good reason, but you need to approach the situation calmly and professionally.  Otherwise, even if you are in the right it will be difficult for other people to take your concerns seriously.

Your comments suggest (to me) that the situation is not as straightforward as your initial post describes.  Without considerably more detail about what  happened — which would be inappropriate for you to post here — it's difficult to make specific suggestions.

I think you need to discuss the situation with someone who understands both the politics in your department and the publication culture in your field.  Find another senior faculty member in your department (or in a different department, or in the dean's office) who you can trust to keep confidence.  (Yes, this can be difficult, but ask around.)  Write up a timeline of events in advance, and make copies of documentation for each event in the timeline.  Calmly and carefully describe the situation.  Just present the facts; don't panic, and don't accuse.  (One of the facts is "I'm scared"; that's okay.)  Ask your confidant how to proceed.  Listen to them.

In the best case, this is a simple misunderstanding, and talking to an informed but neutral third party is the best way to convince you to relax.  In the worst case, your department chair is being egregiously unethical, and in particular threatening your chances at graduation, in which case you absolutely need a senior faculty advocate to help you navigate the resulting political mine field.  (Your primary goal in this case should be to graduate and get out, not to optimize your grade or to punish your department chair.)  Most likely, the actual situation is somewhere in between those two extremes.

Good luck.