my battlelog account has been banned.

Answers HQ cannot handle bans. We don't have access to your account - we can't look into any specific cases. All we can do in here is link to your options.

The following link will show you your options, including how to dispute bans:
https://help.ea.com/article/information-about-banned-or-suspended-accounts

This will tell you in detail about Battlelog rules and bans:
https://battlelog.battlefield.com/bf4/forum/threadview/2832654348586821015/

This page tells more about Punkbuster bans:
https://help.ea.com/article/punkbuster-bans-and-violations

This page is about GCC-Stream bans:
https://help.ea.com/article/i-was-banned-from-servers-by-ggc-stream-how-do-i-get-unbanned

And last, but not least, this page is about Fairfight bans:
https://help.ea.com/article/battlefield-4-ban-codes-issued-by-fairfight