The primary cause of a Mambo (now Joomla) install failing is because of a hacking attempt at your website and the Web Saver's server.
Most attacks cause minor issues with your website, like not being able to view your photos, or not being able to log in to the Admin panel. Some will prevent viewing the site altogether, with a blank white page showing instead.
No matter how it has been affected, please try the following steps before opening a support ticket:
1) Monitor your error log located in "statistics/logs/error_log". Look at the end for any PHP parse errors.
2) Search Google for the error, as this will often result in a fix showing up on the first or second hit.
If the error is as follows or similar:
PHP Warning: Cannot modify header information - headers already sent by (output started at some_directory_and_file.php .....
Check the given file for anything after the '?>' at the end. If there is any code there, remove it immediately. If you don't see a '?>' at the end, put it in.
Try checking the log again, as sometimes it is not just one file that is afflicted.
It is also recommended to then run the command 'chmod 755 file_name' on the file, or change the permissions using FTP to 755 (no write access for both 'group' and 'other').
If your Joomla install is still not functioning as it was, please open a support ticket and a staff member will attend to the problem as soon as possible. Keep in mind that web-site specific tickets will have a lower priority next to server-wide tickets.