Sorry to hear about having to attend a funeral. I don't have a lot of experience with audio on the Mac, but I thought I'd make a few suggestions anyway, due to this being an urgent matter for you.
Audacity is a free audio editor for OS X,
WireTap Studio is a shareware audio recorder/editor, and
Audio Hijack Pro lets you play with audio input from various devices. Hopefully one of those might be able to offer some help...
I'm a bit concerned that you hear no audio on the MP3 player itself. Perhaps the sound is only very quiet and needs amplification? I suppose you'll find out when you try an audio editor and look at the waveform. Good luck!