After another of many crashes, keyboard stopped functioning, though 3 or 4 keys continue unaffected. Nothing at Microsoft approaches problem; HP seems brutally remiss...any uggestions greatly appreciated

Hello,
Have you looked in the device manager under keyboards for any problems Open the Start menu, right-click on Computer, select Manage
Click on "Device Manager" in the left-hand tree try telling your keyboard to update driver.

Yes...also uninstalled drivers [just in case] and reinstallle, all to no good result...ty

It might be that the ribbon cable connecting the keyboard to the motherboard isn't working correctly in which case a replacement is in order, (this happened to me last year)

If the system is still under warranty I'd suggest having it checked out by the warranty repair center (the place that you bought it from can point you at them).