I updated to windows 10 a while ago and everything was working fine for a bit.

After you open Run, type Regedit in the Open: field and click the OK button. Users of Windows 7/10 operating systems often need to adjust the screen brightness. I am a user of MSI GX60 Gaming Laptop and I had a big problem with ATI Drivers, since then I can't update the driver because I will not be able to change the brightness of the screen. Screen brightness setting the screen brightness on the problem. For more information about using the Windows Registry, refer to the Registry documentation. Now the Windows also has this feature in advanced laptops. As you click on Control Panel then Hardware and Sound and Power Options then you can see ‘Screen Brightness’ slider at the bottom of the Power Plans Window. Right-click the power or battery icon in the Systray. It should be possible if windows can it do automatically (Dim display after: x minutes/Turn off display after: x minutes). There are many reasons behind for brightness not working, one of them is graphics problems.

Adaptive brightness windows 7