If you need a quick and dirty way to restore your preferences, here's a way you can do it using a keyboard shortcut on launch:
Windows - double-click the PS icon to start Photoshop
Immediately Hold down CTRL-SHIFT-ALT
You will see a delete preferences dialog. Click “yes".
Macintosh - Hold down CMD-SHIFT-OPTION instead.
Hi thank you for your time. This did not work, the option is still greyed out
I ran an update for the new applications and installed 2018 version and now the function is working, thank you.