EXCLUSIVE

Michael Galeota, star of "The Jersey" on the Disney Channel, has died ... TMZ has learned.

We're told the actor went to the hospital last week after complaining of abdominal pains and left last Wednesday ... against the doctor's advice.

Michael went radio silent over the weekend, and one of his friends went to his Glendale home Sunday to check on him. Michael didn't answer, so the friend climbed through a window and found his body lying in the living room.

We're told Michael had a history of hypertension and high cholesterol. He also battled diverticulitis -- inflammation of the digestive tract.

Our sources say he was not following medical advice. So far it's being treated as a death from "natural causes." An autopsy is pending.

Michael was 31.