Where did all the music go?

So I went to plug in my old ipod into my windows computer and add a bunch of music into iTunes, almost around 3 GB worth. I began the "transfer purchases" (which asked to authorize the computer because I haven't done anything like this) but after it was finished the music were no where to be found. It wasn't in the ITunes library and also in the ipod. I'm wondering where it went. Did it actually all go somewhere or is it all deleted?