Videos doesn't play in my computer

I’m working on a proyect and videos were working but suddenly one day they stop playing. The program runs but videos doesn’t appear. I test the project in a friend’s computer and they worked. What could be happening in mine? Thank you!

Im using windows 64

Is the video on the computer’s hard disk or at a network address?

One guess is the problem might be not having a video codec on your computer that can play that video file.

What happens if you try on your computer with other videos from other sources, or if you try to play that video on your computer using some other video viewer software?