The workers compensation appeals board provides a measure of protection for workers who have suffered a work related injury. Every state has some type of workers comp appeals board- although it may go by a different name depending on where you live. Regardless of what it is called, the purpose of the workers comp appeals board is to review denials of workers comp insurance claims to determine if the denial was appropriate or if the worker should have been granted benefits.
Your chances of winning your case in front of this appeals board are, unfortunately, impossible to predict on a general level. Every single case comes down to the people involved and the evidence involved. If it is pretty clear that the injury arose as a direct result of a work duty, and if it is clear that you are actually hurt or injured, then you should have a fairly good chance of winning your appeal. If your claim was legitimately denied, however, because you did something to disqualify yourself (like coming drunk to work) or because your injuries aren't considered work-related (such as if they happened while you were driving to or from work) then you do not have a very good chance of winning a claim in front of the workers comp appeals board at all.
The best thing you can do to maximize your chances of winning is to understand the process and get as much evidence as you can to prove your claim. You will also want a lawyer on your side to assist you in making your case.