If you dig through responses, a user named Far Isle explained a PERFECT solution….as long as you can access the main screen. Go to Settings, Device Settings & Keyboard option. From that screen, deselect the US English Keyboard and select another country’s English keyboard! I selected both Canada and UK…defaulted to UK on my Kindle Fire HD 10. For good measure I held down the power button until it shut off and then waited a minute before restarting…now the keyboard comes up and types beautifully! (As it should!!)
P.S. I typed this six weeks ago and no issues since!