If your disk is cracked there is pretty much no chance of getting files off of them. I wouldn't recommend inserting a cracked disk into your computer as the thing could shatter and ruin your drive. Are these audio files a music CD or files you created? You've been helped by a 14 year old.
If you've already installed GTA VC then the audio files should already be on your computer, it's usually only the video files that are left on the disk, just to save space. I doubt whether there's anywhere that you can download just the audio files from, though going to the Rockstar Games (<- clicky for the developers' website), might be the first place to look, and going on their forum(s) may help. "I've always been mad, I know I've been mad, like the most of us..." Pink Floyd