Hi!
I've recently updated my Latitude E6420 from Windows 7 to Windows 10 and then I did a clean install. Everything seems to work flawlessly except for one issue. The brightness adjustment function keys stopped working. Now I've read somewhere that some driver updates disable the PnP monitor driver. I've checked the device manager and it was still working. So I've disabled and re-enabled it and voila! They work again. But after a restart it's the same again. What can I do?