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.
Note that it also could be due to the country IP lock, enabled a couple of days ago. You can reset that as well using the password reset page. There wasn't enough detail in your post to narrow down what might be causing the problem, however.