After I upgraded from Windows 8.1 to Windows 10 I am unable to adjust my screen brightness in any way. I have tried using the keyboard shortcut, as well as clicking on the batter icon in the notification section of the taskbar. It is stuck at the lowest setting, making it hard to read my screen in sun. I have also tried restarting and shutting down my laptop, but it did not fix the problem. Please help. Any suggestions welcome!