What could be the sound problem of Asus x550cc?

Question

System administration

Notebook Asus X550CC.
One fine day, the speakers in the Win 7 Ultimate system stopped working.
The speakers themselves are operational, turning the Play Post Sound function to ON in the BIOS-e gave me sound at the Asus splash screen. But there is categorical silence in the system itself.
The sound goes through the headphones without problems.
The equalizer shows the change in noise levels during playback.
The left software was not installed. What could be the problem?
Thanks in advance!

Answer 1

To exclude a hardware problem, start from any LiveCD with a graphical interface and check the sound, it is possible that the contact responsible for switching the speakers / headphones is stuck at the hardware level and after the system boots, the laptop thinks that it has ears permanently connected.

Answer 2

the driver or in the mixer messed up something

Answer 3

That's just the point, nothing has changed

Answer 4

Headphones sound fine

That is - the headphones are stuck - it sounds, they are stuck out - silence? What headphones?
Or how?