By references, if you mean bibliography, do you have "Automatically update citations" unchecked in the document's Zotero Preferences? If so, you might have simply added new citations, but the bibliography requires a manual refresh to appear again. (Skipping auto-updates is a useful thing to do in long documents, so nothing odd about that at all.) By Preferences and Refresh, I am talking about the "Document Preferences" and "Refresh" buttons within the Zotero tab/ribbon in Word, not Zotero itself.

If your bibliography is simply missing, deleted or never added, you can always insert it anywhere in the document you want by the "Add/Edit Bibliography button" next to "Document Preferences". Until you add a bibliography, you may only see the citations.