What is the ruling on the prayer and clothing of someone who suspected that something came out of the penis during the Friday sermon, then found wetness on his underwear after the prayer, while suffering from obsessive thoughts, and then changed his clothes without washing the penis or repeating the prayer? And is what he touched considered impure? And what should he do regarding past prayers?

The cure for waswas (whisperings/obsessive thoughts) is to turn away from them and not pay them any attention. As long as the matter is merely doubt and waswas, then there is nothing upon you, and your prayer is valid and you are not required to repeat it. Nor is a ruling of impurity given to your clothes or to what you touched with your hand after touching your clothes. You must not indulge in them or give them any importance. Nothing is now required of you, neither repeating any prayers nor anything else. Rather, you must completely ignore the waswas and not care about them.