no sound after upgrading iTunes!

hello mates..
i've just upgraded my itunes to the new 10.5 on my macbookpro, during the installation i had some issues writing in the registry! something about files needed to be re-downloaded!!
i restarted my computer and now i have no sound at all, except for the startup chime!!
i went to system preferences but it says: now output/input devices found..
i restarted the computer few times, repaired disk permissions, replaced the battery,reset the rams but nothing solved it....
i had the same problem few months back when i downloaded the SnowLeopard!! but back then it solved its self when i replaced the battery!!

when i open garage band i have the message:

and here's the disabled sound controls:


please help, i can't study without the videos on my computer!!
cheers!

There is no such thing as a 'registry' in OS X.

If the issue was during the iTunes update - go here, re-download iTunes and reinstall it.