iphone 5 speaker problem

Hello everyone . I bought an AtnT iphone 5 just a month ago and used it with great care . But today while playing an application the speaker crashed and then whatever I tryed to play the sound was horrible and very unclear . I think the speaker crashed . Please help me out here and let me know from where can I get the original speaker part for Iphone 5 ? My phone is still in warranty so will the apple store do the repairs for free ? Please paste a link for the part from Amazon , Ebay or inform me if this problem will be solved by apple store . Thank you .