Had a similar issue. Mine turned out to be the result of some recent autoruns editing I had done via the SysInternals suite. I ran across some autoruns involving some old ESET NOD drivers. I haven’t run that for probably at least three or four years, not, supposedly, even on the system, so I nixed them. One was a keyboard filter driver intended to intercept hotkeys related to the program. Anyway, I recalled editing the autoruns so I went back in and restored some possibilities, namely the old ESET stuff. Rebooted, boom, got my keyboard back.