No bother.
(1) If you have not already done so, restart Mac and try again.
If the iSight still does not work, and if you are convinced that none of Apple's suggestions from http://support.apple.com/kb/HT2090 help you, (for example, are you certain that you used the correct "reset" procedure?), yours is most likely a hardware problem that will require a professional fix. I know that is not the answer you want, but sometimes reality happens.
Unless you have a current backup, make one now.
Then use the final "Troubleshoot iSight" suggestion:
"... contact Apple or an Apple-Authorized Service Provider for service."
If you bought locally, your retailer may be able to help you.
If you want to try on-line help, use http://expresslane.apple.com/GetproductgroupList.do
(2) If you want to try one more thing on your own first, use Disk Utility to repair permissions. Then download and apply the latest Combo Update for your Mac OS.
The latest current 10.7 Combo is here: http://support.apple.com/kb/DL1459
The latest current 10.6 Combo: http://support.apple.com/kb/DL1399
Repair permissions again immediately following the system restart that completes the Combo update.
Properly applying the Combo version of updates can sometimes correct problems with software, but hardware problems require help from an Apple technician because there are no user serviceable parts for iSight.
Message was edited by: EZ Jim