Open command prompt(start -> run -> cmd) and type the following command :
C:\> netstat -aon | findstr 0.0:443

Last column of the output is the PID of the application using port 443.

You can find the application name in Task Manager. Go to Process Tab then in Menu Bar of Task Manager go to View -> Select Column -> Check "PID" and press Ok. Search for the PID in the list(Click Below "Show processes from all users" in case if you don't find the PID), corresponding process is the application which is using port 443. Stop or Uninstall it to make your AMPPS Apache work.