my son is incompacitated and unable to speak for himself. he is 44 years old. Prior to him not being able to communicate, his "girlfriend" somehow obtained power of attorney. I would like to know if I will be able to revoke her power of attorney and have it turned over to me. My son is not married
You would have to apply for Conservatorship.
I agree. You have to petition for Conservatorship, and explain to the court why the power of attorney should be dissolved -- e.g. she doesn't look after your son's best interests, or that the power of attorney was obtained while your son was not of sound mind, etc.
It depends on the power of attorney, and whether it was "durable" or not.