You can reset it by running CompleteFTPBootstrapper.exe via the following command.
Note that
1) This must be done from a command prompt that is being run with administrator privileges
2) The CompleteFTP service should be stopped prior to running this command
Version 7.2 and later:
32-bit Windows Vista or later:
"C:\Program Files\Complete FTP\Server\CompleteFTPBootstrapper" "/m C:\ProgramData\Enterprise Distributed Technologies\Complete FTP\config.sdf"
64-bit Windows Vista or later:
"C:\Program Files (x86)\Complete FTP\Server\CompleteFTPBootstrapper" "/m C:\ProgramData\Enterprise Distributed Technologies\Complete FTP\config.sdf"
Versions prior to 7.2:
32-bit Windows Vista or later:
"C:\Program Files\Complete FTP\Server\CompleteFTPBootstrapper" "C:\ProgramData\Enterprise Distributed Technologies\Complete FTP\config.sdf"
64-bit Windows Vista or later:
"C:\Program Files (x86)\Complete FTP\Server\CompleteFTPBootstrapper" "C:\ProgramData\Enterprise Distributed Technologies\Complete FTP\config.sdf"