Hi. Is the use of a third-party library acceptable for this project? If so, I would propose using libsndfile - which has support for various uncompressed audio formats (including WAV format), and would make this much easier.
What do you want / need to do with the raw audio data once it is decoded? E.g., do you need to play it back via the speakers? Save to an output file? Something else? (If you need playback functionality I would need to know more about your sound sytem - and would need to revise my bid also.)
If you can't use a third-party library - and need a WAV decoder "from scratch" - then this would be a 50 USD job rather than a 15 USD job.
What variant of Linux are you using? And would you be able to compile the program yourself if I send you source code, instructions and a Makefile?
I am based in Ireland by the way - I think about 8/9 hours different from India's timezone.