You can email support@zotero.org with the email addresses you've tried, but note that an account isn't required to use Zotero, so it's entirely possible you were just using Zotero locally without syncing. If that's the case, your data would be on the computer where you last used Zotero, and you can just set up syncing to transfer your data. If you do have Zotero running locally on another computer, you can check the Sync pane to see if you previously set up syncing with a different account.