Power failures are funny (NOT!) things. Did you open the alsa mixer
(right click the speaker icon) and see if one of the channels got muted? Maybe that's all it is. Are you able to play other sounds (like .wav files) using some of the utilities or hear sounds with other utilities?
What about possible corruption? Have you done an rpm --verify to see if something got corrupted or removed?
Sometimes power failures are associated with a surge or spike. First step is to make sure the hardware is still good using some other utility to test it, like I mention above.
Or, like it happens to me many times after a firefox crash or a reboot by example, some previous updates are finaly taken into account upon restart, with a few surprises... If you can hear sound in other applications, maybe try to remove the .macromedia and/or .adobe/Flash_Player directories...?
JD