Running the following from the command line should give you a new password:
cd cron cron> php reset_superuser_pass.php your-site.com newpass
You will need to replace your-site.com with the actual domain/hostname that you use to access FileRun in the browser. If you do not specify newpass, a random one will be generated and displayed in the command's output.
You might find additional information on running FileRun command line scripts here: Command line tools