Apple have encouraged people to use their email address as the ID, but the fact that you're no longer using that email address does not prevent you from getting into your Apple account. Your email address and your Apple account are two separate IDs - they just happen to be the same text.
You do however, need to remember the password for your Apple account, not least because the "forgot password" feature that Apple use will send a reset to the email address on file which, if you haven't changed it, will be the email address that you cannot access.
However, this only matters if you have purchased music (or anything else) from the iTunes Store (which you will have done with your original ID). But if all your music is from CDs or other online sources (such as Amazon, Bandcamp etc.), then you do not need your Apple ID.
What you do need is the complete Music folder from your old computer, which also contains the iTunes control files which tell iTunes Library where all your files are located, pasted into the Music folder on the new computer. You may need to direct iTunes to the .itl file in the Music folder when you first open it.
JonBillups wrote:
... i transferred my itunes library to and itunes account on my new computer with my current id. I now cannot sync music with my ipod and new computer without wiping out my 5000+ songs on my ipod.
Your device (the iPod) can only be synchronised with one iTunes Library. If you attempt to Sync with another Library (i.e. your moved one, in the new iTunes Library on your new computer), then the new iTunes will remove the content of your iPod and replace it with the content of the second Library. Going back to what I said before (in the third paragraph), if all your music is from sources other than the iTunes Store, there should be no problem. But the iTunes Store purchases made on the original account will not be available to you.
If Genius was set up in the original account, then it will not be available in the new account, since it is not the account that set it up.
The first thing to do is check to ensure that the music listed in your new iTunes Library plays (check as many songs as you can). If all your music is useable in the new iTunes Library, then simply let a Sync replace the existing content of your iPod with the new content, which will be the same content.
If you purchased music from the iTunes Store, then you need to sign into the account that paid for that music.
