Jalcom wrote:... Firewire is not longer supported with Mountain Lion?...
Not true. External iSight works fine with my '09 Mac Pro and 10.8.4.
Jalcom wrote:... So I am wondering if something wrong happened ...
So it must have.
Jalcom wrote: ... help me with it!...
You have tried several good things, but there may be other suggestions from http://support.apple.com/kb/HT2090 that you have not yet considered. Be sure to check more than one Apple app in more than one user account to help you pinpoint the cause of your trouble. Then you will know what to fix.
In addition to the Apple troubleshooting, check your > System Preferences... > Sound > Input to verify that your iSight's mic is selected, not muted, and that its volume setting is properly adjusted. You may need to check this again after restarting Mac or changing apps that use the mic.
Also, be certain that the apps you are testing are configured to use iSight's mic. Different apps select the mic in different ways. For example, QuickTime X allow selection among various microphone alternatives via one of its preferences as shown in the image below:

(I was using my Display microphone and did not have my external iSight connected when I made this image. Therefore, there is no iSight mic shown in my list of mic choices above. If your iSight's mic is properly connected, turned on, and recognized by your Mac, iSight will show in your QTX microphone preference choice list.)
If you are trying to use your iSight with a Flash based web site, also check your Mac's > System Preferences... > Flash Player > Camera and Mic settings to verify that your Flash system preferences are not blocking your mic.
Some other apps may offer mic and or camera selection via their application menus. If you have trouble finding out how to select the iSight internal mic in other apps, check each apps' Help or post back the name of the app whose selector you cannot locate here so we can try to help.
Message was edited by: EZ Jim
Mac Pro Quad Core (Early09) 2.93Ghz OSX 10.8.4 24" LED Cinema Display External iSights