Your account has never been banned. Most likely, you (or someone else) tried to log in too many times with an incorrect password. This causes a temporary IP lockout. Wait 30 minutes to 1 hour and try to log in again, or if you cannot remember the password, you can reset it at https://en.nostalrius.org/password.
If someone was trying to hack your account by trying common passwords, then it looks like they were unsuccessful.