If you can no longer access your website and instead see a message such as "Bandwidth Limit Exceeded", then your Web Hosting account has likely exceeded its allocated Bandwidth Quota for the month.
As a website becomes more popular and traffic to the website increases, it is necessary to consider upgrading to the next web hosting account. Accounts which use all of their Bandwidth quota for the month are automatically suspended and any websites on the Hosting account will be inaccessible until the account is upgraded to a higher capacity Web Hosting plan or until the quota resets on the first day of the next calendar month.
To ensure your Web Hosting account does not go over it's allocated quota, you should periodically check your account usage to ensure it is within it's limits (see related article). You should also ensure your contact email is correct as the server will send a notification email for accounts reaching their quota limit.