What to do if I’ve been diagnosed with carpel tunnel and the doctor said that my state’s workers comp usually denies such claims?

It's not illegal for the doctor to give you a recommendation or to advise you what he has experienced in the past.  However, every case is different, so you should proceed forward with your claim.  If you are concerned that your claim is not being handled properly, consult with a worker's comp attorney. Worker's comp is a type of law often referred to as administrative law.  You will want someone who is experienced in your jurisdiction in handling the administrators of your local program.

As a side note, you may have other options other than simply looking for another job.  Consult with the same attorney and your HR department about filing a request for an ADA (disability act) accommodation.  Depending on the extent of your injuries and the type of work at your employment, you may be able to simply get a new assignment.  However, if you don't specifically request an ADA accommodation, then you will not get the protections of the ADA.

It would be advisable to file your workers' compensation claim.  Your employer's HR department will have the documents you need to file your application.  Only the evidence presented will determine whether or not a claim is denied.  The evidence will include the medical reports documenting the extent of your condition and medical restrictions, and your job description.  If your employer cannot reasonably accommodate your medical restrictions, you may be eligible for vocational rehabilitation for a different job.