Hello, my friend's account was banned due to spam or plagiarism, but he didn't do anything. Most likely it was banned by mistake, please check.

Username - alkashik13, bitcointalk profile - https://bitcointalk.org/index.php?action=profile;u=1561866;sa=summary

He received a message:
Sorry alkashik13, you are banned from posting or sending personal messages on this forum.
You have been permanently banned by a forum moderator, probably due to spam or plagiarism. You may appeal here, but your chances are not good: banappeals...@bitcointalk.org