Files are there, but they don't play ???

I wanted to access some multimedia files today and I realized that they don't play.
I remember copying them from an SD Card weeks ago (Therefore, most likely it was a FAT formatted Card).
What can be causing this?
Files exist with original file size, but they don't play (tried in different players).

right click on one of them and look at it preferences and see what file format and how big[mbytes] the file is, and check there location