HP Envy 15-3200 is an excellent laptop but if you have installed Windows 10 update, you will be facing the brightness issue. There is a fix for this brightness toggle problem in Windows 7 and Windows 8 but that would not work in Windows 10. Fortunately, there is a solution.
Download this reg file from here and double click on it to install it on your HP Envy 15-3200 running Windows 10 operating system. You can also do it manually by following these steps.
Press win + R
press ctrl + F
In following directories, find “FeatureTestControl” and change his value to “0000ffff”
And now reboot. Of course, you can just install the registry key mentioned earlier to fix it.