After reinstalling a lot of driver on the google. I finally make the FN + F4 Function key to work.I have installed this driver and it work well for me (I'm using Dell Precision 7510)Realtek High Definition Audio Driver | Driver Details | Dell Vietnam
 Hello, Im using Laptop Dell Precision 7510. Since I bought the device, all function keys are working fine but until I reinstalled windows 10 because I want to reinstall windows on my new M2 hard drive. And after reinstalling windows as well as using Intel Driver Support Assistant to check driver up-to-date, my "microphones mute" function key doesn't work anymore, all other function keys can be used normally. Can anyone have this problems and anyone know how to fix it?I also read the "Mute Microphone" Function on F4 Key Not Working" on the forum. But the problem have not fixed  
"Mute Microphone" Function key (F4) not working