audio language change with window media player 12.0

This is a very unclear question.

Are you asking how to change the language of the text that is used in the interface of the WMP player ?

Any audio source file is likely going to be recorded in only one language (okay, I suppose you could have a stereo audio file with one language on the right channel, and one language on the left channel).

If you are talking about conversion of audio source in one language to another language: then good luck, and if you get this done, you may well receive a Nobel Prize ! :) Speech-to-Text in one language has remained one of the most complex, and insolvable, problems in Artificial Intelligence for decades now.

So, what, exactly, do you want to do here ?