I highly doubt that you were banned for that, check your email...

Microsoft have ran out of way's to ban people now.

Tut, tut, tut..

You should realize that anything you do, from the day you sign up to live, to the day you get banned, everything is on record, so if you modded it in the past then put it back to the original they can still ban you for what you did months ago.

Misa-Campo wrote I highly doubt that you were banned for that, check your email...

This email is to notify you that your Xbox LIVE account privileges have been permanently suspended due to modification of your gamertag or other profile data.

These modifications may include, but are not limited to:

Altering the appearance of your gamertag or avatar
Illegitimate gain of achievements or avatar awards
Application of watermarks or other special identifiers that were not legitimately granted
Unauthorized manipulation of in-game parameters

Your conduct was brought to the attention of the LIVE Enforcement Team through complaints filed by other Xbox LIVE users or in the course of our operation of the service. The LIVE Enforcement Team has reviewed the complaints and other evidence regarding your conduct and determined it violates the Xbox LIVE Terms of Use and/or Code of Conduct. Because your conduct is in violation, the LIVE Enforcement Team has issued a permanent suspension.

During your suspension, you will not be able to log into Xbox LIVE. Your Xbox LIVE privileges will not be reinstated.

Customer Support is not able to modify or provide any further details about your suspension.

Microsoft expects that all customers abide by the Code of Conduct. The Code of Conduct provides guidelines for appropriate behavior while using the service.

You can view the Xbox LIVE Code of Conduct from the Xbox LIVE Dashboard under Xbox LIVE Policies in Account Management, or by visiting xbox.com/legal/codeofconduct.htm.You can view the Xbox LIVE Terms of Use by visiting xbox.com/legal/livetou.htm.

Note: if you are not a user of Xbox LIVE, this suspension may have been enacted due to your activity in the Zune Social. You can view the Zune Social Code of Conduct by visiting zune.net/legal/codeofconduct.htm. You can view the Zune Social Terms of Service by visiting zune.net/legal/termsofservice.htm.

Thank you,

LIVE Enforcement Team

This is something irreverable I think. :/

i got banned for life for having a blue avatar and hacked gamerscore, i know i shouldn't have done it and there is no point doing it but banned for life is quite harsh...

No. With the new dashboard you can't sign into your banned accounts, or unban an account. Only the XBL staff can.