If the administrator account is locked, you can use the recovery mode to reset your password:
Edit FileVista\Filevista.config and do the yellow highlighted change, i.e. change value False to True
<RecoveryModeEnabled>True</RecoveryModeEnabled>
For older versions, edit FileVista\App_Data\Filevista.config, the setting was like this so change the value 0 to 1:
<add key=" RecoveryMode" value="1" />
After the change save the file and then go to the login page, enter username (eg. admin) and leave password field empty and login. FileVista will let you in and then prompt you to enter a new password.