My ipod is locked with my old Apple ID and I can't sync my new purchases to it

I haven't used my Ipod Touch since 2013 and since then I have changed my email address which also was my Apple ID. I created a new Apple account with a new ID last year but didn't think about the Ipod and now it won't let me change the ID on the ipod. I remembered the password once as I managed to log into the ipod but have not been able to do so again. But even when I logged into the Ipod itself, I could not change the ID. How the heck do I change the ID on this so I can sync my new music over to it?

Thanks!