If you're banned on alteriwnet, oh my oh my. You're banned.
There are many methods of unbanning yourself, posted here. If one of these does not work, try the next one.This is to minimize all threads in the forum begging for unbans. Be aware, these unban methods are for dynamic ip only.
[WORKING] Method by Markus - Spoofs your MAC address, which generates a new XUID.
[WORKING] Method by wafflele - Changes your MAC address, which generates a new XUID.
[SEMI-WORKING] Method by Batfitch - Download the attachment named "Alteriw Xuid Spoofer.rar" and run it as administrator. Apparently it still works for some people.
[WORKING] My Method w/ General Shep fix - Spoofs MAC Address, which generates a new XUID; also included IW22 fix by GeneralShep.
This will be updated when new methods are presented. Remember, if you have static IP, you must contact your ISP for a new IP (or use some other method) that's all I know of. Dynamic IP, well you're lucky.