Trackpad stopped working on mac book pro 2019
Removing a preference list is not so good on macOS. First step is to let the database that tracks preferences to clear those entries.
defaults delete -/Library/Preferences/whatever

Since the system may not read those settings, shut down after the above. Good news is you know the hardware and OS are fine. Worst case no one can help figure out how your account is corrupt and you back up your files and restore them to the new account with the working settings.