1
If pressing the F1 key does not disable Mute, try pressing Fn + F1.
If that works, try pressing Fn + Esc to disable the function lock on your keyboard.
2
Also, click the audio icon on your Taskbar at the bottom of the Desktop, if there is an X on the icon on the left of the audio slider, if you click that icon, does that un-mute your audio?
3
If that does not un-mute your audio, right click your Start Button and open Device Manager.
Expand the 'Sound, Video and Game Controllers' section.
Please provide a screenshot of that full Device Manager window.