No Audio Output Device is installed

Hi,

I have an MSI EX630-034US notebook with Vista Home Premium. I recently sent it back to MSI to fix a noisy fan, and so, my computer performed many updates when I got it back. It was working for a few days, and then today while I was watching a video, the sound became scratchy. I muted it and unmuted, but still scratchy. Then I muted it, and there was no sound. I restarted my computer and found a little red x over the speaker. I right clicked the speaker and looked at my Playback Devices and only the HDMI port's audio was listed. Also, under recording devices, neither my internal microphone nor my input jacks were listed. I researched a little online and was led to look at my Device Manager. Under Sound, Video and Game Controllers, Realtek Audio HD Manager, was listed along with my HDMI audio. On the Realtek, there were no yellow "!"s present and my driver was up to date. I tried disabling and enabling, but that didn't help either. Then, I restarted again. This time, there was no section of my Device Manager called Sound, Video and Game Controllers and my HDMI audio was not listed under my Playback Devices, nothing was listed. Windows Update had SP2 available for me, so I updated. Upon restarting, nothing had changed. So, I ran sfc /scannow and the only problems were with Windows Sidebar.

Should I try to install sound or chipset drivers when my computer isn't recognizing the hardware? Could this be a hardware problem, like a broken sound card? Any help at all would be greatly appreciated.

Thanks

 

I will try that if it stops working again, thanks! It has sound again mysteriously this morning. Last night, I restarted and my HDMI port's audio was back, and my computer was looking for drivers for some "Other Device" but nothing would stick, not even the MSI drivers. But now it works. I'll probably be back.