Windows 8.1 Audio issues

Hi all,
I’ve just installed 9.5 pro and when I start it, it knocks out all the audio on my system… has anyone else suffered from this and if so, what’s happening? and how can I sort it out?
It’s just seems to mute everything, even music playing in the background.
Also, when I tried to view the tutorials, again, there was no sound…
Please help?