Q: I purchased the drummers bible and the audio files don't work

Hello JRook789, 

That is a bummer that the audio content is not playing. I would start with deleting the book to remove it from iBooks and then download it back again to see if the audio starts to play from you. Take a look at the article below to walk you through this. 

How to delete content you've downloaded from the iTunes Store, App Store, iBooks Store, or Mac App Store

http://support.apple.com/en-us/HT5772

Download past purchases

http://support.apple.com/en-us/ht2519

Regards,

-Norm G.