This really shocking me when i open my website, it displayed an error with reason "The password of the account has expired"
Hastily i open my SQL database using 'sa' and check the login with that account.
It turn out that i check 'Enforce password expiration' on its properties.
And when the time reach the limit, the account cannot login to database.
The solution was just un-check the password expiration on the properties & write again the password.
i refresh the website and wheeuuh...that solved the problem.
:)