Who can help me out with my built-in iSight issue?

Okay, so I have a question regarding my built-in iSight.

Now, I know... This question may have been asked before but I just can't find it, I guess it got lost in the mass.

If you would be friendly enough to forward me the message or instruct me on what I need to do to solve this, that would be a great help.
Also, I'd like to know if I have to reset anything will I lose everything on my Mac? Should I make an external backup?

So basically the issue is that whenever I turn on Photo Booth the only thing I get is a black screen.
The program will let me take a picture, but when I want to see a preview of the image, it's not there.

I then tried to use my iSight with iChat, which worked perfectly fine. After that I did the same with Skype,

but Skype didn't let me see anything but black as well.

Can anyone help me please?? Is this an issue that can be fixed myself or should I bring it to the Apple Store?

As this is a very important matter to me, because my parents are moving out of the country soon and I would like

to keep in touch through Skype, I would really appreciate all the help!!!

Thank you in advance guys!