Windows – brightness control stops working after latest windows 10 update

I have googled this issue and tried every single solution that has come up.
All my computers' brightness controls have stopped working.
Some broke after the creators update, some broke after the latest update.
Some locked the brightness at minimum with the control grayed out and some give the option to change it but clicking it does nothing.

EDIT: Specs:
PC#1: HP Compaq 8510w
https://imgur.com/fOe70V1
Broke after Windows 10 creators update
I'm running the latest NVIDIA drivers, I tried going back one version and even tried installing the OEM drivers to no avail
Brightness on this laptop is locked at zero, even if I boot into Windows 7 and change the brightness it is set back to zero
Brightness function keys do nothing

PC#2: HP 6730b
https://imgur.com/17HHLDT
Running latest Intel GPU drivers
Broke after Windows 10 update 1803 (latest)
Function keys do nothing, brightness appears to be at the value I set it before the update

PC#3: Gateway One ZX6980 (desktop)
https://imgur.com/QpA7eQS
Running latest Intel GPU drivers
Broke since release of Windows 10
On this one the option to change the brightness completely disappeared from the menu after the Windows 10 upgrade

Edit2:
PC#4: HP 2000
Interestingly enough the function keys for brightness work on this laptop however the brightness control on the Side Bar and in the mobility center do nothing

My desktop is too bright and laptop is too dim now.
The Gateway desktop shipped with Windows 8.1 and the laptops shipped with Windows 7

Nobody seems to know a solution and posting on the Microsoft forums/answers only yelds the generic troubleshooting steps.

Don't mind the "activate windows". I tried a fresh install to no avail.