Videos on iPhoto

I imported some videos from my camera onto iPhoto and they all worked at first. When I went back to convert them for iMovie about half of them stopped working. I was able to retrieve some of these from Finder, and they worked when I opened from Finder (although they still don't work in iPhoto). I can't find about 4 videos in Finder and they won't open in iPhoto. Of course I hastily deleted them from my camera in a short-sighted error in judgement. Any suggestions? I'm really screwed here, these are for work.