I have a terrible problem, I can not write my name and I can not play on servers or worlds of friends this happened to me when this renaming and wrote §6§8§5§3 and then not let me put clear name and nothing.

I have a terrible problem, I can not write my name and I can not play on servers or worlds of friends this happened to me when this renaming and wrote §6§8§5§3 and then not let me put clear name and nothing. please helpe