When you get a Photoshop error said “Could not open a scratch file because the file is locked or you do not have the necessary access privileges. Use the properties command in the windows explorer to unlock the file”
Fix: delete the preferences setting
Best and Quickest Way to Fix: hold down Crtl + Alt + Shift keys during phtotshop start up. It will ask you if you want to delete the setting, click ok to delete it.