restoring/changing/altering or actually being there is indeed impossible. But all that data is not lost. I mean altough you cannot travel back in time, you can still see that data, if you knew how to use it.(i mean non-pre recorded camera.)

another thing is that you know that things like about hearing the sound of the lightings a bit later or like when you look at the sky you dont see the actual place of the sun but you see where it was 8 mins ago... then if we could travel faster than light, we do something and get into that device and travel somewhere and when you look back, you should be seeing yourself doing what you just did.