Hi all,
I followed the steps under the HP support site to use the Windows troubleshooting guide to fix problems with the audio:
http://i.imgur.com/p7BDHqX.png
I updated the driver to the latest driver, audio plays but there are no devices installed
http://i.imgur.com/IWNVef0.png
Downgrading the driver to the older version doesn't fix the issue either.
I also used the HP recovery manager to ensure I had the original version installed.
I don't have a previous restore point to go back to.
I had BIOS version F.25, followed advice in this thread installed driver
sp55036.exe, and also flashed my bios back to f.22 (which was when around the time I purchased the laptop)
Any advice/ help appreciated.