Macbook 5.1 WebCam Drivers

Hello and thanks to all for your help in advance.

I want to help a friend with her mac and she is having a problem with the webcam builtin her computer.

I believe the webcam model is Isight, seems that its not been recognized anymore by system, she cant see it anywhere, and i wonder if the webcam drivers got uninstalled somehow.

If so, which is what i think happened, how and where can we get the drivers for her webcam?, how we could install them and how we can know that the webcam has been installed properly?.

Please explain this to me in an easy way so she can do it by herself, she is no Mac expert.

Thank you very much for your help and kindness.

Oscar.