@Dj64Mk7 A workaround is to hit "Switch User" on the lock screen and see if that allows the keyboard to work. Try doing a
PRAM and
SMC reset (as a basic troubleshooting measure) as well as checking for the latest updates in Windows Update.
"...hit "Switch User" on the lock screen..."
The screen I've been talking about this entire time is the one BEFORE that, where it prominently displays the time and date. There are no buttons to speak of. [I don't mean to sound rude or condescending, but are you familiar with Windows 8/8.1/10, or versions of Windows before these, such as Windows 7?]
Anyway, creating a second user and switching to that user, then back to mine (so as to end up on the sign-in screen for my account) does not solve the issue.
I tried doing
both a PRAM and SMC reset, and neither of those solved the issue, either.
We're quickly running out of things to try. Once again, I'm sorry for putting you through all this trouble.