What I need is an API/Library that will allow me to convert .wav files (or other media files is necessary) to their text equivalent. Does a library/api like this exist?
This is rather typical Question. Anyhow depending on the language you are using there may be many different choices.
Java http://voce.sourceforge.net/
PHP http://www.speechapi.com/ and http://cmusphinx.sourceforge.net/
Basically, the best option for you is to use some online cloud-based API, that will take your .wav input and return you the response in the text.
In this way, your API will be accessible from any language and will take a lot of pain out of your code.