Argthtjtr

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.

Fixed by Microsoft as of yesterday in KB4284835:

https://support.microsoft.com/en-us/help/4284835/windows-10-update-kb4284835

Addresses an issue with the brightness controls on some laptops after updating to the Windows 10 April 2018 Update.

On my HP Envy laptop, I realised that after updating windows, sometimes the monitor in Device Manager gets disabled automatically. I enabled it and immediately the brightness changed.

Right-click on "This PC", click on "Manage", choose "Device Manager" from the left-hand menu. Under "Monitors", right-click on "Generic PnP Monitor". If the device is disabled, you should see an "Enable" option. Click on it and the problem should be solved.

For the laptop, try the Windows Mobility Center, which has several controls on it, including one for brightness.

Two ways to access:

1. Right click the start button, and click Mobility Center


2. Press the Win + R shortcut keys together on the keyboard to get the run box, type "mblctr" (without the double quotes), and hit enter.

This won't work on a desktop, however, unless... you unlock the feature.

Follow the directions here: https://winaero.com/blog/mobility-center-desktop-windows-10/

In short:
Open notepad and save a file named MobilityCenterEnable.reg

In the notepad, paste:

Windows Registry Editor Version 5.00



[HKEY_CURRENT_USERSoftwareMicrosoftMobilePCMobilityCenter]

"RunOnDesktop"=dword:00000001

Save the file, and double-click the file to run it.

Now you can run the Mobility Center on your desktop, and there would be a brightness control there also.

Windows 10 has several known problems with brightness controls,
but it is still astonishing to have the same problem on two
completely different devices.

This is a list of workarounds that worked for some people :

• Restore power defaults
  
  In Control Panel > Power Options, click Change Plan Settings and then on
  Restore default settings for this plan. Do this for all your Power Plans.




• Disable Adaptive Brightness
  
  In Control Panel > Power Options, for your active power plan click
  Change plan settings, then Change advanced power settings.
  In the Power Options dialog, expand Display and then expand Enable Adaptive Brightness. Set all of them to Off.
  
  These setting are worth a look if you have then : Display brightness,
  Dimmed display brightness and Enable adaptive brightness.




• Disable the Intel Power Saving Technology
  
  This setting is found in your Dell or Vaio Control Center.
  For more info see
  this article.




• Disable the BrightnessReset task
  
  Open Task Scheduler and in the left pane expand Task Scheduler Library.
  Navigate to Microsoft > Windows > Display > Brightness (if you have it).
  If you see on the right a scheduled task called BrightnessReset, double-click on it, choose Properties > Triggers tab > Edit, then disable it and see if it works for you. A reboot might be required.



• 
  

  Run the Power Troubleshooter
  
  You may access it via the Windows 10 Troubleshooters Settings Page or run the following command directly to bring up the built-in Power Troubleshooter

  
  
  

  msdt.exe /id PowerDiagnostic
  
  

  
  



• Registry change
  
  Use regedit to go to the key
  HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlClass{4d36e968-e325-11ce-bfc1-08002be10318}.
  
  If you see any items named KMD_EnableBrightnessInterface2 or
  MD_EnableBrightnesslf2, set them to zero and reboot.




• Power troubleshooting
  
  For further troubleshooting of Power Plans, use the built-in
  PowerCFG command line tool.

I don't know if you have fixed the issue, but as for me, the problem was that my high contrast theme, which I accidentally tried, saved to my Microsoft account.
No matter what I did(reformat, re-install drivers) it always reverted back to a high contrast them at start up. This was because my Microsoft account was auto applying the theme at sign in, then wallah! High contrast is on even with a fresh install of windows.

In the 1803 update there is no option in the(settings->ease of access->high contrast) theme of "None" to apply to your Microsoft account, so that it might save to the Cloud/One Drive or whatever it backs up too. That option was removed from 1709 version.

After 6 hours with Microsoft support (with an out come of "you need to call your manufacturer, you probably have a hardware malfunction." or "your Nvidia Drivers are not yet updated for the new 1803 update") I got them to set me up with a USB drive with the 1709 version.
Once I was on that version of windows, I went to high contrast themes, selected a theme, clicked on the apply high contrast theme button (this was so it saved to my Microsoft account), then selected the high contrast theme of "none" and clicked apply. Now it was saved to my Microsoft account.

I still had to restart my computer 3 times for the "none" high contrast theme to load at start up. I suppose it took that long for it to save to my Microsoft account.
Once that was done, I turn off sync settings to Microsoft account in the settings->updates, I think.

I believe, but do not know, that the 1806 update turns "sync themes to Microsoft account" back on by default.

This reverted my colors back from neon, having to ware sunglasses to use google, to the nice Matted but full colors that I was used too.

Hope this helps.

I had the same issue turns out it wasn't a display driver issue at all it was just the monitor driver. Go into device manager then under monitors check what your monitor says mine said PNP Monitor Standard I had to update the driver and use the manually select from a list option then select Generic PNP Monitor after that everything worked like before.