How to get music off iphone onto cpu under these circumstances?

So my cousin's music was on his mp3 and he moved it to his phone without saving it on itunes and then deleted it all off his computer. So it isn't saved in itunes or anything but is on his iphone… How do i get them back onto his computer? They don't pop up on itunes or anything.

Added (1). 1.cpu is my computer's autocorrect for computer
2. That doesn't work because the songs weren't purchased from itunes ect. They were off his mp3 and aren't saved in itunes at all really. Its a hard to explain situation.

FYI: Music doesn't go in to the processor (CPU) it goes into the hard drive. You have to open up iTunes then click the iPhone. Right click the iPhone from the left side bar and click transfer purchases and wait for all of his songs to transfer to your computer.

"how" is it on his iphone if it's not in itunes? Is it on a card, or in an app, or what? What is he playing them with?