HOW TO DETERMINE WHAT CODEC I NEED, AND WHERE I FIND IT ?

HOW DO I TETERMIN WHAT CODEC I HAVE , AND HOW DO I INSTALL THE CORRECT ONE ?

Exactly what are you trying to do?

[u]MediaInfoOnline[/u] can tell you the format of almost any audio file.

[u]FFmpeg[/u] will you to import/export almost any audio format with Audacity.

Is this question related to Audacity?