I recently changed my apple ID. Now when i go into sign on thru ipod touch (4gen) its say i need to follow insctutions to verify (email) Emails says thanks....... your email has been verified. Go to sign on and says "account has not been verified".
Go to Settings->Store, and make sure you're signed out. Then restart the iPod and try signing in again. Also, make sure you don't have any issues with your WiFi connection or have some firewall enabled that could keep it from accessing your account properly. You also have the option of emailing iTunes Store support via www.apple.com/support/itunes and selecting one of the topics.