HT4895: Using your Apple ID for Apple servicesLearn about Using your Apple ID for Apple services
Without having enabled Find My iPod on it before it was lost then there isn't any way to locate it. And even if you did have it enabled you would only be able to find it if it's connected to a network and the device hasn't already been wiped and/or Find My iPod disabled on it.
If you think that it was stolen then you should report it to the police. You should also change your iTunes account password, your email account passwords, and any passwords that you'd stored on websites/emails/notes etc.