The error message is telling you that the database "a3655963_PHPVMS" is not found.
Is there any changes to your database recently? If yes, find the new database where your phpVMS is and update your local.config.php.
Please take a look in your local.config.php by going to core/local.config.php
And find the code simlar to this.
define('DBASE_USER', 'username');
define('DBASE_PASS', 'password');
define('DBASE_NAME', 'myva_phpvms');
define('DBASE_SERVER', 'localhost');
And update it to what your database access is.