My apple ID is NOT working ?

So my iPod got stolen, and before, I was using y friends apple ID because I didn't know how to use it and was new to iTunes and all that ish. So like I said, it got stolen and everything was erased from it. When I got it back o had my friend put all the stuff back on it. But his account was disabled because of security reasons, probably me, and I had to make a new apple ID so I could use iTunes and the app store. Well, everytime I go to buy an app or song. It pops up "apple ID and password: (his ID) " even though I'm signed into mine, I don't know how to fix this problem. I have done everything possible except whipe out ALL my stuff again, I don't have any of my stuff saved on a computer because I can't download iTunes on it. WHAT in the world do I do?!?