Hi,
If you're speaking of Linux, the script is in <EM Home>/bin/EMCtrl.sh. In Windows it is <EM Home\IntroscopeEnterpriseManager.exe (if you're starting it manually) or if you're starting it as a service, then go to windows services and start it from there.
EM Home is where you installed Introscope.
Can you elaborate more on taking the default path?