Need old music transferred to new computer
Your old Apple ID is probably still valid and I imaging the old password will still work.

For example, if I have an email address blahblahblah@something.com and create an Apple ID it's just using that email address as my username. It is not actually using your email account's password to authenticate. Does that make sense? I'd just try logging in with your old Apple ID (email address) and your last known password.

If all else fails then I hope you had a rescue email address setup for your Apple ID!