Hi passline711,
I understand you would like to transfer an iTunes library to a new computer. The following article provides various options for doing so:
iTunes for Windows: How to copy purchases between computers - Apple Support
If you need assistance recovering your Apple ID information, you can reference this article:
Frequently asked questions about Apple ID - Apple Support
Apple recommends you change your Apple ID to your current, working email address. This will not create another Apple ID, it will only change it to your working email address. See Changing the name you use for your Apple ID if you'd like more information.
Note: @mac.com and @me.com Apple IDs can not be renamed. If you no longer use the .mac or .me email address be sure to add your valid email address as an additional email address.
Thank you for contributing to Apple Support Communities.
Take care,
Bobby_D