Q: icloud keychain incorrectly entered to many times

Hi haohung,

Thank you for visiting Apple Support Communities.

It sounds like your iCloud Security Code was entered too many times and you need to contact Apple Support, as mentioned here:

If you enter your iCloud Security Code incorrectly too many times, you can't use that iCloud Keychain. You can contact Apple Support, who can help verify your identity so that you can try to enter your iCloud Security Code again. After a number of incorrect attempts, your iCloud Keychain is removed from Apple's servers, and you'll need to set up iCloud Keychain again.

From:

Frequently asked questions about iCloud Keychain - Apple Support

Click the link above or go to http://www.apple.com/support/icloud/contact/ to contact Apple Support.

All the best,

Jeremy