If your VLC version is too old, have some wrong settings or lack of necessary software support, then VLC will not play DVD. The most common problem might be the software problem. And software problem could be the player compatibility and the DVD hardware glitches. But generally speaking, there are several causes which lead to the VLC not playing DVD problem.
The reason why VLC fails to play DVD may vary based on different computer configurations and playing environments.
Part 2: How to Solve VLC Won't Play DVD.
