Hi,
I posted about this problem about a week ago for my G73jh. I had tried all the things this and other forums said to do, but nothing worked. I spent another 10 hours on it and finally downloaded this from the ASUS support site:
ATKPackage_WIN7_32_WIN7_64_z100005.zip
I installed the ATK0100 file, rebooted my computer, and ran Life Frame (also downloaded from ASUS support site). Life Frame started up and the green light went on the webcam. I could see myself on the screen and I could take pictures and video. First time in the ten months I've owned my laptop.
Hope this helps. KP