Expanding on Orange's explanation, by changing the file extension, you just change what programs can view the file. It is not meant to be converted to .txt or any word processing format, because .mp3 files store more than just the song, but also song information, such as artist, ratings, album, etc. and changing this data destroys the integrity of the file and you likely will not be able to play it. In all honesty, you should just use programs that are designed to create music files, otherwise you will corrupt the file. I believe the language you're talking about is binary, octal, hexadecimal, etc. etc. convert into ASCII (which is what a word processor does to the file). This machine code was used back in the early 50's (and earlier) for computer programming, before programming languages like FORTRAN or assembly languages, etc. were developed. . . Or something like that.
To get back on topic, this isn't my area of specialty -- I'm currently in the middle of my second year of environmental engineering.