Then try another external keyboard that's known to be good, and you'll have your answer.   My guess is that you're experiencing keyboard failure which, while it takes a lot longer to occur with conventional keyboards than laptop built-in keyboards, can and does occur.

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Brian - Windows 10 Pro, 64-Bit, Version 2004, Build 19041  

The purpose of education is not to validate ignorance but to overcome it.
       ~ Lawrence Krauss