See Download your past purchases - Apple Support for access to your past purchases. Note that anything that shows in your library as in the cloud needs to be downloaded to your library before it can be transferred to your iPod. Most people only require a single Apple ID. Creating more than one account leads to unnecessary complications.
iTunes remains a free application. Yes Apple may try to suggest you join Apple Music, but that is an ongoing subscription. You might find it useful, since it will let you listen to anything in their catalogue while you have an active subscription, however those tracks cannot be copied to an iPod classic so I suspect it isn't quite what you need.
The information at Empty/corrupt iTunes library after upgrade/crash would help if had previously had your media on the current computer and it had stopped showing after a crash or update.
The information at Recover your iTunes library from your iPod or iOS device would have helped if the media was still on your iPod and you had stopped at the point where iTunes asked you to confirm if you wanted to remove whatever was already on the device and replace it with what was in the library. Since you allowed iTunes to proceed it is now too late to recover that media.
The user tip Backup your iTunes for Windows library with SyncToy details how to make a security copy of your iTunes library, and indeed any other data you consider important, to insulate you from the effects of a failure of your computer's hard drive, user error, or some other disaster.
iTunes may be slightly quirky at times, and not everybody's favourite software, but Apple are not responsible for the death of your previous computer. It would seem Best Buy took away any opportunity for you to recover data from your old drive, but you should have been taking steps to back up that data before the computer died. Having failed to do that you should have taken steps to secure what was still on your iPod before that too was lost. Again, not Apple's responsibility. You could argue that Apple could do a better job of warning you of the consequences of syncing your device, for example stating exactly how many tracks would be added and how many would be removed, I wouldn't argue, however there will have been a warning which you either didn't interpret properly or simply assumed you could ignore.
The combination of your old email address and password should still function as a valid Apple ID allowing you to recover the purchases made from the iTunes Store on that account, barring any that have since been removed from the store by the rights holders. See https://iforgot.apple.com/ to try to gain access to the account. It is obviously more complicated to retrieve an account if you no longer get the email for its address, however it may not be impossible. You can but try.
I've emphasized the text above because too many people assume that when they get a new computer all they have to do is sign into iTunes with their Apple ID and all of the media that they had ripped to their previous computer will be there. This is not the case. You need to actively back up and transfer your data to the new computer. Apple do have a subscription service called iTunes Match which can provide access to your own tracks on more than one computer, but it is no substitute for a properly made backup of your own.
tt2