What should a young man do concerning his father's forbidden work in a cafe that serves shisha and drinks: should he ignore him or advise him, and would he be sinful if he advised him and his father refused?

Clarify to your father the prohibition of his work which involves serving shisha. Advise him gently and courteously, without harshness. Do not abandon enjoining him from evil deeds out of an assumption that he will not respond; for your duty is only to command and forbid, and the responsibility falls solely upon him if he does not respond.