How to unlock my ipod

Password, or passcode ? The latter is a four or six digit number used to protect an individual iOS device: if you have forgotten it you will have to erase the device (which I assuming is an iPod Touch). Please see:

If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

If it's saying it's Activation Locked then you have to enter the ID and password used to lock it.

Find My iPhone Activation Lock - Apple Support