Most of our PALCS Windows HP laptops have "Function Keys" at the top of the keyboard. These will often have very useful features such as Speaker/Microphone mute, Screen Brightness and Airplane mode.
By default you will only have to press the buttons themselves to activate their features, however there is a "Function Lock" that can prevent those keys from being used. At the bottom left of the keyboard is a key that says "FN" which is the Function Lock indicator. (This is similar to CAPS lock and NUM luck which also alters how the keyboard works)
When the indicator light is turned on, the Function Lock is on and the top row of keys will operate as normal "F" keys instead of their special features. If you hold down the "FN" key it will allow you to use the extra features.
To turn off the Function Lock, press and hold the "FN" key and then press the "Shift" key right above. This should disable the Function Lock and turn off the indicator light, restoring the top row of keys to use their special features.
Note: The Speaker and Microphone mute buttons also have an indicator LED. When the LED is it means their respective functions are muted (a light on the Microphone button means the microphone is muted).
These can also be toggled by software but the hardware buttons are a good place to look if you are having trouble with the Speaker or Microphone.