My music deleted! What Should I do to recover it?

I have an iPhone 5s, and ios8 came out today. My tech savvy friend decided to install it on my phone, but in doing that, he deleted all of the music on my phone. How do i take the music that was deleted and transfer it over to my iTunes on my laptop? On my phone, the music still shows up, but it will only play connected to Wi-Fi, as the music is no longer saved. Is there any way to recover the music on my phone, or do i have to contact Apple to redownload it all oto my computer?

You can kiss it goodbye. It better to re download it than getting your head heated up.