I agree with DaveM121's response. There were issues with the Windows updates last fall and early winter.
As of April 2026, it appears the issue might have been resolved through recent Windows updates. A week ago I had to turn off my laptop. After turning it back on the next morning, I was able to sign in. Previously, the only way to get the keyboard to work and for me to sign in was to restart the laptop yet again.
If anyone is still having the issue, I suggest installing the Windows updates first. Otherwise, restarting a second time should work. Also, I suggest backing up files to a portable external drive, regardless, to protect your data.