No speakers or headphones are plugged in, HP620

Hello everyone.

I have problem with my sound/sound card.
My notebook is HP 620, product number WS730EA#BED, OS Windows 7 32bit.
Audio driver is IDT.

This notebook has HDMI outport and couple days ago I connected it with my Toshiba TV, which you can connect with HDMI cable.
So I connected notebook and TV and there was picture but not sound.
In sound options I made Digital Audio (HDMI) as a default device, so I can have sound on TV, and there wasn't any sound. I restarted my notebook and there was the same problem - there wasn't sound on TV again.
I disconnected notebook from TV. There wasn't sound on notebook either. As a matter of fact there is no sound to this day.
In IDT audio control panel everything is muted and it's impossible to unmute speakers or headphones.
Device Manager doesn't see problems with soundcard. It says that everything is OK.
On speaker icon is red x and says "no speakers or headphones are plugged in". When I troubleshoot it, it can't fix it and it says that it is disabled.
I tried with updating the drivers - doesn't help.
Uninstalling the drivers and reinstalling it - doesn't help.
In control panel -> sound says that HDMI is not connected (you can't disable it), speakers are default (but you can't configure it) and headphones are default (you can't configure them also). When I go to the recording devices the sound control panel just freezes....
So I thought that problem is with the sound card and I bought the external USB sound card. In BIOS I disabled the integrated sound card. So I installed the external sound card. Everything installed like as it should be. The notebook recognizes the external sound card and says that everything is ok, but again I have red x on sound icon and again I have no sound via external sound card. I rebooted the notebook, same problem.

So integrated or external sound card - I have no sound. Nothing helps, I tried everything to repair it, but it doesn't help.

PLEASE HELP ME !

THESE ARE PROBLEMS IN WIN7, WHEN I'M IN LINUX UBUNTU I DON'T HAVE THESE PROBLEMS. PLEASE EXPLAIN