Unhappy [Q] Screencast Problem

Okay Guys, I have a very noobie question I guess but this is what I'm facing.

I've just made a screencast awhile back and the video has been saved for like 3.86GB. So it's fine. But when I open the file, there was an error stating,

"can't play this video"

So i transferred it over to my PC and it is the same thing as well. How can I recover this video of mine back ?

Help is appreciated .