How do i get to an old itunes account?

I had an itunes account about 2 years ago, and now that I have an ipad, I would like to have all of that music that i purchased on it. Only problem is, when I set up my ipad, I entered an all new apple ID. I can't really remember the one that I had a couple of years ago, but there are only 2 email addresses that it could be associated with, my home and work. How can I retreive all of that info? Or if worse comes to worse, I have the itunes folder on my desktop, can I import that somehow to my itunes on my ipad? I have already tried to email the itunes folder to myself, and the ipad won't recognize it. I obviously have no idea what I am doing. Any help would be appreciated! Thanks!