1. Change CD-key (to a valid, unbanned key) also make sure you aren't launching the game through steam so your key doesn't auto reset to your old one.
2. Change IP (only necessary if admin IP banned you too) you can do this by resetting your router if you have a dynamic IP or just waiting a while (few weeks or so) if you have a semi-static/static IP. It depends on your ISP. You can try calling them to change it too.