Final answer:
In 'The Kite Runner', Kamal no longer speaks because he has experienced a traumatic event where he was assaulted by Assef.
Step-by-step explanation:
In the book 'The Kite Runner' by Khaled Hosseini, Amir and his father Baba hide in a basement with Kamal and his father while fleeing from their home country. Amir learns that Kamal no longer speaks because he has experienced a traumatic event. Assef, an aggressive and violent character, sexually assaulted Kamal, causing him to become mute.