ah, ok.
So let me list what I can think of:
services.msc : Windows Audio must be autimatic and running
Volume must be ok. Not muted (well... just for completeness
)
In the Control Panel - Audio Settings you should try to check "output devices" etc. Also make sure there is nothing muted, etc.
Realtek should have installed an own software. Check all settings (disable SPDIF) and try the sound check there.
Have a look whether anything yellow appeared in the device manager after the reboot.
Try to plug in ear phones and check sound of them. Do they work?
Make sure the external volume control (this little wheel on the chassis) is not on silent.
Maybe I said something that stupid that it helped
Good luck.