Big problem with sound

Hello there, i got a problem that is weird like Jessica Parker when doing duck face.
I have a Toshiba Satellite C855-17X, and since last windows reinstallation i have a problem. Most of the time when I turn on laptop, I can hear windows startup sound, but when it loads completely, and when I try to open music player, or go to Youtube, there is no sound. There is no windows sound effects to.
But there is a weird solution for all that: when I go to Playback Devices, and right click on speakers, than TEST, it starts working. Everything gets okay, music player works, youtube works, but sometimes it stops again after couple of minutes.
What I tried:
1. I tried SFC /SCANNOW
2. I tried to reset BIOS to default
3. I tried to reinstall audio drivers: Driver Details - Toshiba
4. I tried to turn off all startup programs, and all non-windows services
5. I tried to cry all day long.
Additional information:
When i try to play something on foobar player, i get this error message:
Unrecoverable playback error: Unknown error code (0x8889000F)
(That is before i click TEST on Speaker sound device)

That was a MOBO's drivers on toshiba site.
Intel doesn't have any relation to this problem, that's HDMI audio driver
Firstly I thought that your idea about installing the original realtek drivers was bad, and i was right (they weren't working) (also, when i tried to install original intel graphic driver, i got a black screen, and figured out that only toshiba's software works).
But as I had nothing to loose, i tried it, but after uninstallation of current drivers, and restarting windows, i got a pop up ballon, that said: installing drivers. And it downloaded drivers from microsoft update, and it seems to work now.
Thank you for your help, but i will say for two days if it is working fine.

It's working excellently , i restarted laptop 10 times, and it still worked .
Thank you very much for your help :)
Case is closed.
Conclusion: try out windows drivers first