Banned for no reason????????!?!?!? ?!

My friend zhangyixiang got his account banned. He can't login or do anything. I am writing for him since he cant communicate in English very well. He got banned for no reason and is very sad. He wants to quit but I told him I would get his account back. Can you unban him or tell me the status of his account? He is silver 1 and has spent a lot of money on the game. He says that his account can't be found when he logs in