I don't know what caused this to happen. Until last week I had no problem with this Dell laptop running Windows 10.

The keyboard is fully functional as proven by opening an office document (word, excel etc) or other application. All keys cause the correct response.

However while in the Windows environment, even using Sticky Notes, any keystroke is unrecognized by the system and will not display a character or result in an action eg. Return key.

I've tried the basic stuff like running a keyboard troubleshoot and deleting/reinstalling the keyboard driver. An onscreen keyboard works.

I can use a word processor to type in a character string, copy with right key mouse, and then paste into the Windows search box, Run field or a Sticky Notes page and click the operate button to get the function I need. But the keyboard doesn't do anything.

Please advise a cause and solution.

Michael