You can reset the Photoshop Preferences one of two ways. The first is with a keyboard shortcut: When launching Photoshop, Option-Command (Mac) / Alt-Control (Win) + Shift prompts you to delete the Adobe Photoshop settings file (which stores your preferences). Note: there is a very short window between clicking the PS icon to launch it and needing to hold down the keyboard shortcut, so get your fingers ready ahead of time!
The second is by manually moving and renaming the file. this video shows you how:
Another example of Adobe lack of consideration for the end user. Why have such a complex and error prone procedure. So many things Adobe should do here.
A. Provide a link in preferenes to open up the preferences folder.
B. When using the keyboard shortcut technique, why not give the user the choice to just reset the preferences, save the preferences in a standard backup location and send the old preferences to Adobe for analysis automatically.
This could be achieved with a few lines of script or code. Computers are perfect platforms to eliminate tedious, difficult or risky tasks. Instead, Adobe asks their users to adopt this procedure.
Also, there is no reference how people should remember all of their preferences, so they can re enter their previous settings.
I have a script which backs up critical files in hard to find places into a date stamped zip file. I did this initially for Microsoft normal.dotm file, which is often the target for hackers. At 6 am every morning I have set my PC to wake,automatically back up these files. I added another script at the same time to backup any new or changed pictures from my production drive to my online backup drive. I will add the Photoshop preferences to this process with a single line of script. If I end up with a Photoshop preferences issue, I can then find the last working preferences file and send the good one and the bad one to Adobe. Unfortunately few Adobe Photoshop users have the skills to do this.
If Adobe had any consideration for their users they would automate this task.
Sorry for the long post.