Hello DinhThien,
This issue should have occured if you have used any of the services beyond allocated limits as suggested in the below link:
http://www.windowsazure.com/en-us/pricing/free-trial
You can find which is the resource that you have overused from the link: account.windowsazure.com by clicking on subscription and then on overview for the subscription.
If you need clarification, you can reach out to support:
http://www.windowsazure.com/en-us/support/contact/
The way out of here is to either wait till the start of new billing cycle to see the subscription in active status again or remove the spending limit if you are using it for a production environment.
Note: Removing spending limit would mean that you agree to pay for any charges that would incur to your account for the overusage.
Regards,
Lancers
