Problem with Video playing in GOM Player

Good evening everybody,
I contain more than 10,000 video files. Most of the files are in .flv format files. All these videos are played perfectly before.
At the time of formatting my system, I got backup them in DVDs. Now, when I tried to play them, some videos played, but don't support sound system. Some videos not played completely.

- You don't have necessary codec to play.
Please Click "Find Codec" button to the right side.
Codec Finder will help you to install Codec.
- If Codec Finder cannot find the appropriate codec, check your file first. It may be damaged or fake file.
