Try to Force-Quit the Finder on the Mac. (command > option >esc). Then see if PS pref is found. If not, then go to the Cloud and download and reinstall PS again.
One idea is to hold down the cmd-opt-shift keys and start Photoshop. It will ask you if you want to delete the settings file. Answer "Yes" and it will create a new Preferences files. Photoshop should continue to load.