Why are my photos black?

I am thinking of following your guide to replace the LCD screen on my DMC-FX07, but I am not sure if it is definitely the problem. Yes I can turn on my camera, and the screen is black. However the crosshair is still visible on the screen, and would I see that if the LCD screen was the problem? Moreover, when I plug the camera into the computer the photos are black, so it is not just that I cannot see them on the camera screen.

Could the lens be the problem, and if so is it fixable/ replaceable?

Ruairí