Banned

Recently I was banned from forza 4 online for 20 years I have done nothing wrong I want to know the reason for me being banned

Hacking of the game and contents, and attempting to sell the illegally modified car on the Auction House, in violation not only of the Xbox Live Code of Conduct but the copy protection of the game developers with reverse engineering of the game code will result in a permanent ban.

Code of Conduct:
" F. Cheating & Tampering

Do not cheat in a game unless the developer has deliberately enabled cheats.
Do not use unauthorized hardware or modifications.
Do not exploit game vulnerabilities or glitches.
Do not make unauthorized modifications to your account profile or its contents, including but not limited to tenure, Avatar, saved games, Gamerscore, or achievements.
Do not intentionally play with someone who is using unauthorized software or methods.
Do not play any illegitimately obtained software or pirated games.
Do not take any action to cause degradation of service for Microsoft or other users, including but not limited to network interference or manipulation.
Do not play a game before it has been authorized for play on the service."

See also the back of Xbox game boxes: “Unauthorized copying, reverse engineering . . . or circumvention of copy protection is strictly prohibited.”