I bought this iPod from some one and I don’t have the username/password or any of that information and neither does the person I bought it from. What can I do?

So the person you bought it from does not know the details of the person who owned the iPod? Ask yourself why this is.

I would ask for your money back. After all, why should you pay for something that doesn't work?

And now the seller doesn't want to respond to you. Again, ask yourself why this might be.

If you bought it through an online auction site, or similar marketplace, you should use that site's appeals procedure to get your money back.

Alternatively, you could try reporting the matter to the police. They will of course, need some sort of contact details for the seller.