You have discovered one of two features: If the number on the script title bar (right side) doesn’t read “1”, then you have used the Script Switcher feature which lets you edit more than one script at a time. Click on the left arrow to get back to your original script. If your script was “replaced” by a single page with the name of the script, you have discovered an upper level to scripts designed for advanced users. Just double click on the page to get back to your script. Both of these features are covered in the manual.