Dell Vostro Notebook Keyboard locked in Windows 10 pro

The keyboard does dot respond in Windows 10 pro. The most recent update is not installed. The keyboard works flawlessly when not in Windows but appears to be locked in Windows. Mouse and on-screen keyboard work as expected. Device manager shows nothing wrong. Cannot start in safe mode as on-screen keyboard and mouse not accessible at the selection screen. Google search shows this to be a fairly common issue but no suggestion tried did anything.