Message a mod or contact support to see how long your brother is muted for.
If it's his first mute, it'll likely be an auto-bot mute, meaning it should only last a day.
Further offences after that will extend how long you would be muted for, 1 day to one week to 1 month to 6 months, or after that your chatting capabilities may be removed altogether
My brother got his account muted and it showed no date nothing when he will get muted. Does that mean he got permanently muted or chess.com will randomly some time later unmute him. I am really worried tho about his account as he took months playing and practicing in it as well as made tones of friends. It is really valuable to him