Just a thought, to check that your problem is not related to corrupt main windows keyboard program drivers, you could try restarting you computer in 'Safe mode' and check if the problem is not present in 'Safe Mode'.
If you are using Windows 7, restart your Computer and before windows starts keep pressing the F8 key rapidly to access the 'Safe Mode' Menu option.
If using Windows 8 or 10, firstly access the usual Windows Shut Down / Restart menu options and when you see the 'Restart' option hold down the keyboard 'Shift' key and then click 'Restart'. Keep the shift key pressed and windows will eventually restart and display an Options screen, one of the items being 'Troubleshoot', then,
-Click 'Troubleshoot'
-Click 'Advanced options'
-Click 'Windows Start-up Settings'
- Select 'Enable Safe Mode'
- Select 'Restart'
Windows will restart to a 'Advanced Boot Options' screen. Select 'Safe Mode' and when Windows starts in Sfae Mode check status of keyboard keys.
If your keys work in safe mode, then it will most likely be an issue with the main keyboard program drivers, which should be easier to sort. Fingers-crossed.