The driver for your model is available from here.....
You must re-boot after it installs.
EDIT..>>> Before installing the Audio driver (download and save to your desktop) create a restore point.. start> rightclick computer> properties> system protection> create.
Download and install, BUT do not run yet, Driver Sweeper......
uninstall your audio/sound driver from add/remove programs and re-boot into Safemode(F8).
YOU MUST COMPLETE THESE STEPS IN SAFEMODE.....
1.)Double click Driver Sweeper to open.
2.)Put ticks in any box that says Sound beside it.
4.)Click Clean ... you will need to run the clean button twice as to clean any residual left overs.
Re-boot into normal windows and click out of any "found new hardaware" prompts. Install the Audio driver that i linked for you, follow the prompts then re-boot your machine, it is important that you re-boot so that your system recognises the changes.
Edited by odin88, 08 May 2011 - 10:03 AM.