What is the movie title with Jerry Lewis in it where he played the part of a TV repair man who was the missing son of a rich family and he didn't know it?

The movie you're referring to is "The Nutty Professor." In this film, Jerry Lewis plays the role of a shy and clumsy professor who, through a potion, transforms into a more confident and suave version of himself. However, it seems there may be a mix-up, as the plot about a TV repairman and a missing son aligns more closely with "The Family Jewels," where Lewis plays multiple roles, including a TV repairman.