Did you get banned by Warden/Blizzard?
Sorry dude, if you got banned by Warden (Blizzards anti-cheat software), you have no chance to get unbanned. You need a new cd-key and a new bnet account.

You got banned on a banlist or a ghost++ database? No problem!
Follow these steps to play again:

What is banned?

The ghost++ bot can not ban your cd-key, because this key is only known to you and the blizzard wc3 server. So it bans your account name. The name is based in a database and if you try to join the game again the bot kicks you. Some bots also ban your IP-adress.

How to bypass?

If you are only banned by name, you can just create a new account and join the games again.
However if you are banned by IP-adress it is becoming more complicated. A IP-adress is a unique identifier for your internet connection that is given to you by your internet service provider(ISP) and identifies you in the world wide web. But you are lucky, the ISP changes your IP-adress at least all 24 hours. That has different technical reason, e.g. many ISP have more customers then IP’s. To bypass the IP ban, you can just restart your internet connection(e.g. restart your router or dsl modem).

Also good to know:

If somebody says he would ban your “IP-Range”, he is just an idiot. Yes of course he can ban your range, but if you are for example customer of the ISP T-online, a IP range ban would cause very many players to get banned – maybe even the admin himself.