Is it an account ban or IP ban?
If it's an account ban, you shouldn't post again on a second account - contact the mods/admins as to why you were banned.
If it's an IP ban, then you might be using an IP address used by a banned user - a common example being proxies/VPNs which are often banned as spammers/socks/PBUs tend to use them. Switching IP addresses will help.
Hope that covers everything