My Trackpad doesn't work on my MBP when I unpaired Logitech mouse I had Logitech mouse paired to my MBP/Capitan. I used Logitech Unifying Thing to unpair the mouse. Mistake: now no mouse, and no trackpad response. Keyboard still works. Rebooted MBP, no change. Is there a way to bring MBP trackpad back using only kybd?
@Allan recommended booting into safe mode, so 3rd-party extensions wouldn't be loaded. This brought the trackpad back, and I was able to run the uninstaller.

I also found that merely unplugging the Logitech transceiver dongle freed the trackpad. No reboot needed.