Is the repentance of a young man for his disobedience to his father accepted and valid, with his effort to please and honor his father, and is there a worldly punishment for that?

The one who repents from a sin is like one who has no sin. Allah's mercy encompasses all things. The questioner should strive in obedience to Allah and in honoring his father. It is not permissible for a father to taunt his son with a sin from which he has repented. If he does, the son should be patient and advise him gently, explaining that he fears sin for him. If the father does not cease the taunting, it does not harm the son, and he must continue to obey and honor his father.