Please Do not post anything about bans on the forums, for it is against the rules. Contact a Mod/Administrator in PM and discuss. If this person was banned, it was probably because they were misbehaving, Mods don't ban for no reason. You do not know if your friend did something.. against the rules.
Discussion on Bans and Reports
You are prohibited to make a thread or mention in a post about being kicked and/or banned from ingame or on the forum. If you were kicked and/or banned, then it was for a reason. If you have a question about it, however, then you are referred to a moderator or an admin. As for reports, do not go and make a thread reporting a user. When you are reporting somebody, you are to send a private message to a moderator of an admin for them to handle it. Any threads discussing a kick/ban or reporting a user will be deleted upon sight.