Sony cyber shot video upload problem!!?!?

Ok when I upload my videos from my cybershot to my pc the videos are uploaded working fine and playing,but when I disconnect the camera from the laptop and saved them the videos and go back on later to edit them,the videos won't play they are just black.I use power director 8 and when Im about to edit my vids on their I get a message say error and some other stuff,for all my vids and I just press ignore all.my videos are weren't saved on the pc and were deleted by accident,but I was making a vid and saved it with the videos in it,but they are just black and not playing.how can I fix it the videos won't work for any edit software and player.I can't get them back so I have to just try and fix them from the movie they are in.please help.thank you