If you click File | Online | Check for Update but then cancel the update installation (or get an error), Grapher will no longer be installed. If the download of the EXE file was completed successfully, it was saved to your hard drive. You can use this file to rerun the update and reinstall Grapher. The location of the file on a computer with Windows Vista or newer is:

%AppData%\Golden Software\Grapher

Navigate to that folder and double click on the installation EXE file to begin the installation procedure.

Updated March 13, 2020