How can one atone for the sin of stealing a friend's phone without directly disclosing it to him, due to fear of his negative reaction?

Theft is one of the most heinous crimes forbidden in Islam. The thief must offer sincere repentance and restore the rights to their owners, even if through indirect means, and it is not required for him to admit that he is the thief. If the stolen item is damaged, its value must be returned. Repentance is not complete except by returning what was rightfully taken, as the Prophet, peace and blessings be upon him, said: "The hand is responsible for what it took until it returns it."