What Does it Mean When Your Apple ID Has Been Disabled for Security Reasons?
Your Apple ID provides a convenient means of accessing Apple content, applications and services from your computer or mobile device. An Apple account keeps your credit card information on file, allowing you to purchase items without re-entering your information for each purchase. To prevent unauthorized users from purchasing items using your account, Apple disables your Apple ID if it thinks that your account's security is compromised. To regain access to your Apple account, reset your password using the iForgot service.
If Apple disables your Apple ID for security reasons, this means that you --- or someone else --- tried to access your Apple account, but entered the wrong password multiple times. If you forgot your Apple ID password, then tried to guess the password but guessed wrong several times, this could be the cause of the account disabling. Otherwise, the "This Apple ID Has Been Disabled for Security Reasons" message may indicate that someone else has been trying to break into your account.
When your Apple ID is disabled for security reasons, you can no longer edit your account information or purchase music, movies or applications from the iTunes or Mac App Stores. If someone has, in fact, managed to break into your account, this disabling prevents him from charging purchases to your credit card or accessing your personal information. If you use the MobileMe service, Apple also blocks access to certain features of your MobileMe account.
To re-enable your Apple ID, reset your password using Apple's "iForgot" service. Enter your Apple ID on the iForgot webpage, then choose whether you want to re-activate your account through email or by answering the security questions that you created when you started your Apple account. If you choose to reset the account through email, click on the link in the email from Apple, then type in a new password. If you want to reset the account by answering the security questions, enter your birth month and date when prompted, then type the answer to each security question that appears. Enter a new password when you're finished answering the questions.
Once you've changed your password, enter the new password into all of the programs that you use to access your Apple account. You'll need to change the password that iTunes stores, for example, as well as the password stored in the App Store on your iPhone. If you're using MobileMe, update your password for this service by double-clicking "MobileMe" in the Control Panel on a Windows machine or the System Preferences section of a Mac computer.