no audio output device is installed (HP ENVY 700)

I have no sound at all on my pc , either with my headphones or with the basic sound of the pc . I can not access the volume mixer. I have verified that my drivers are up to date . In recording device there is nothing, no audio device is installed in recording and sound.
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Exploitation systeme : Windows 8.1 64 bits
Model : HP Envy 700-339