I was lucky - I got brand new computer from one of my best friends for my birthday! But just few days after something went wrong - I could not access my video files. I tried few simple ways to get there - I double clicked on each file, I selected some and pressed enter, but nothing happened. I restarted computer with same negative result. Finally I realized there should be problem with the hard disc. Well, as I said, I am lucky - it is brand new computer and problem happened during guarantee period, so I simply took the whole thing to nearest service center (fortunately it is in my city and is not as far as London!) and got it repaired!