My computer has lost its sound

Maybe you accidentally hit F3? Try putting your
volume all the way up with F5. I doubt this is your
problem, but see if it is and report back to us.

Matt

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I just bought a tune from the iTunes store as a further check. The song plays! I can hear it! I must be making some stupid mistake that prevents me from hearing a video clip that I have been enjoying until just now. Here's the clip:
http://www.metacafe.com/watch/277863/defendingyour_wife_and_beatinganother//
It's quite funny, and a friend I sent it to also thinks it's a thigh-slapper. I just can't figure out why I can no longer hear any of the sounds from the clip.

This pops
up from time to time where another app changes the
MIDI sound preferences and as a result, your sound
vanishes. Try opening Garage Band and playing one of
the sample loops. This resets the prefs to the
defaults and if that was the cause of the missing
sound, you sound will return.

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I couldn't find any sample loops, but that's probably because I've never even clicked once before on Garageband. I did manage to play some notes on a keyboard, but that didn't help. Still, your advice sounds good, and I'll fool around with Garageband when I get back from a trip I have to make tomorrow. Thanks for the tip. I hope this isn't a sample of what my MacBook is going to be putting me through in the future. I never had anything like this with my iMac.

Do you
have any sound at all? Any system sounds or sound
through iTunes?

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Yes, as I mentiond before, I can hear the song in my iTunes library that I just purchased from the iTunes store. Now I'm getting ready for bed, and I won't be back until the day after tomorrow.

Do you
have any sound at all? Any system sounds or sound
through iTunes?

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The problem has been corrected enough to satisfy me.

I just downloaded that troublesome clip again, and I was able to hear the sound. On the other hand, I still can hear no sound on the several clips that I sent to friends and myself. In other words, when I click on the links that I sent to myself and my friends, I can view the clip, but there is no sound. I guess that will have to do; I'll never know why some clips have sound and some don't, but the important thing is that there is sound on at least one of the clips. It's a funny skit, and I'd hate to lose the sound. Thanks for your help.

I don't know what finally happened, so let's just close this case.