Lost original Into The Future disk

Don't know if you are still looking for a solution here, but I'm afraid that only EA Customer Support can assist with entitlements to games and expansion/stuff packs. That is, when their systems are working correctly. If your ITF disk was purchased from a recognized and authorized re-seller, then perhaps something is/was wrong with your Origin account that they can fix, but there shouldn't have been any need to buy another disc if the first one was registered to your account correctly. Might you have ever had two different accounts along the way, such as by switching email addresses?

It doesn't matter if Origin recognizes that you have purchased TS3 Store content like worlds or other items. For those, Origin only acts as an optional purchasing agent, not a registrar. The store content, once purchased one way or another, is only available for download from the store itself and it's the store that needs to recognize that you have purchased those items.