Media keys on your keyboard stopped working

The problem

The media keys / the function keys that your keyboard comes with stopped working for some reason. They worked before, but they stopped working after doing something.

The solution

HID (Human Interface Device) service stopped running. This services lets your keyboard do cool things. For whatever reason, it got disabled or turned off. My guess is that you installed a program or system update that disabled it.

How to turn it on

In Windows 7 or 8

1. Start --> Search
2. type services.msc and hit enter
3. Look for HID (Human Interface Device) service and turn it on. Go into the properties and set the option to auto start.
4. Problem solved. System reboot is not necessary.