F2 and F3 keys no longer working properly (no longer adjust brightness level)

[MoGi-21]

Up until yesterday, the function keys to lower (F2) and increase (F3) the brightness level used to work perfectly. However, upon yesterday they suddenly stopped working.

Whenever I press F2 or F3, the slider (to show the brightness decreasing/increasing) doesn't appear, and my screen doesn't dim or brighten.

However, the buttons don't seem to have lost functionality, as whenver I'm using Google Chrome and I press F2 the page refreshes and whenever I press Fn + F3, the 'Find' prompt appears (as if I've pressed CTRL+F). So the laptop clearly still registers that the buttons are being pressed.

I've tried troubleshooting the issue through 'Troubleshoot' --> 'Hardware and Devices' and at first attempt, it said there was an issue and that once I restarted my laptop it would be solved, but upon doing so, the F2 and F3 keys still don't function properly.

I've run out of ideas for what to do, all help is appreciated.

P.S. I've discovered that the F4 button also isn't functioning properly, although I rarely use the F4 key so this isn't as much as a priority. However, F5, F6, F7, F8, F9, F10, F11 and F12 work fine. 

EDIT: I can still adjust the brightness, but I have to do so manually through Settings which is somewhat tedious and annoying since I'd have to do that every single time.

[banhien]

@MoGi-21 

Please try newer software for brightness hotkey

         https://ftp.hp.com/pub/softpaq/sp81501-82000/sp81790.exe

or

         https://ftp.hp.com/pub/softpaq/sp85001-85500/sp85423.exe

Regards.

[MoGi-21]

I tried both links (restarting after each installation) and unfortunately neither seemed to do the trick.

Any other ideas?