Sound suddenly stopped working

I've had WMC up and running for about a year now, no problems. Tonight we decided to watch a movie that I have as an *.mkv file - we do this all the time, at least once a week if not more. I shut down WMC and played the movie in VLC Media player. When I went to start WMC again, the sound was gone.

The sound works in the rest of the system. I can hear computer sounds, and VLC and other media players work fine. It's just WMC that has no sound.

I checked all my devices and drivers, no errors. Though to be honest, if that was the problem I'd expect all sounds to be gone.

I removed WMC from the system by using the "Remove Windows Features" in Control Panel, and then re-installed it. No difference.

I did notice however that removing and re-installing WMC, I didn't have to re-setup all my channels, etc. The settings "stuck". (Oh, by the way, I did re-run the sound setup in WMC, no difference).

I'm wondering if maybe my WMC settings are corrupted somehow? Is there some sort of config file perhaps?

Any ideas? I have no backup plan here, this is my only way to watch TV. I guess I could wipe the drive and start from scratch, but I'd prefer not to. (And I'm worried what happens if that doesn't fix it).

You check the Volume mixer settings for the Windows Media Center.
Here is how:
1. Open Media center and live tv or movie.
2. Right click on the Speaker icon on the task bar.
3. Click on "Open Volume mixer".
4. In the Windows Media Center mixer drag the till you get the adequate sound.