Sound gone

This afternoon, I tried to listen to a local radio show on their stream, and I got no sound. I figured it was the player they have on the site, but then I tried to listen to another streaming radio show that uses Windows Media Player for Mp3s The player opens, the indicator starts moving, but no sound. I checked the volume control on the player - OK. I checked the speaker icon on the taskbar, and the green level line is going up and down, but I'm getting no sound. I tried some files on my hard drive, no sound. Real Player, no sound. All of them open and indicate there's a file being played, but I get no sound through the laptop speakers.

This make any sense to anyone?

Do you have an 'actual' volume control anywhere on the laptop - like a wheel ? I had one on my last lappie - must have caught it one day and accidentally turned it down - didn't even know it was there! I had no sound for a few days until I found it. Doh!

The sound is not muted - it's a laptop, no sound card, no external volume knob - I ran the audio troubleshooting app from MS and it didn't find a problem.

I restarted in Safe Mode and got the sound back eventually. I still don't know what caused the problem. Thanks for the suggestions.