Take d help of parents n teachers Report d matter to his parents Encourage him to talk to someone adult Take d help of cyber authority
Many children/students who has become a victim of cyber bullying loss there confidence and often become depressed. Firstly to help a friend of yours you need to ask him to talk with his parents about it, or if he can't try to be open with him and ask him to tell everything they say so that he feels better.Next ask him not to use internet/social media for some weeks and leave it completely for some time and ask him to visit a counsellor so that he could come out of anxiety and get back his confidence.Help him with studies by studying together and give him some time to get back his confidence.