Hi lgrieves,
Thank you for using the Apple Support Communities! We understand you created a new Apple ID and lost access to some data that was attached to the previous Apple ID account. We're happy to help out.
It sounds like you had this missing data associated with iCloud on the previous Apple ID account. In this case, you're hoping to get that missing data back, so you can associate it to your new Apple ID account. When you chose to sign out of the previous Apple ID on your Mac, you should have been asked to either delete the data from your Mac, or keep a copy on your Mac. What did you choose to do?
When it comes to transferring iCloud data from one Apple ID to a new Apple ID, you would need to make copies of the information that you want to keep from iCloud following these steps: Archive or make copies of the information you store in iCloud. Then, you can set up iCloud under your new Apple ID and choose how you want to use iCloud to access your content: Access your iCloud content on your Mac
Best regards.