This i.e. SCP Toolkit can really muck up your config and with windows 10 can be hard to fix since you cannot force a safe boot from a hard reboot. They say “ScpToolkit is a free Windows Driver and XInput Wrapper for Sony DualShock 3/4 Controllers”.
I didn’t find the following links helpful.
The problem was that the utility had (on instruction) overwritten the mouse and keyboard drivers. Without a keyboard, it was not possible to login and use the tools to remove or revert to the previous drivers.
I fixed it by removing the keyboard and controller, performing a hard reboot with a different mouse and using the “Ease of Access” interface to login and use the SCP Toolkit Wipe/Clean utility to remove the erroneously installed drivers.
This would have been less fraught if there had been a recovery disk or restore points. I must read up on how W10 creates and uses restore points.