If your vBulletin forum has been hacked then it is likely that you will want to change the database password so that you are protected.
In order to make the password changes you will need to go database management and change the database password. After that you will need to log into your hosting account and change vBulletin Configuration file. Here's how:
1. Log into your web hosting account with your username and password.
2. Now locate the file config.php. It can be found using this path: /includes/config.php.
3. Around line 62 and 63 you will find the settings $config['MasterServer']['username'] and $config['MasterServer']['password'].
4. Now replace the password that matches the database password and save the file.
Example text from the config file.
// ****** MASTER DATABASE USERNAME & PASSWORD ******
// This is the username and password you use to access MySQL.
// These must be obtained through your webhost.
$config['MasterServer']['username'] = 'your_forum_username';
$config['MasterServer']['password'] = 'your_forum_password';