You accidentally deleted an item from Zotero, then emptied the trash. Now your Word document shows errors for that citation.
Before fixing the issue, it helps to know why it happened. Citations usually break when: how to relink citations in zotero
If you have a document with many broken citations and manual relinking is taking too long, you might be tempted to unlink and start over. This removes the ability for Zotero to automatically update your bibliography later. You accidentally deleted an item from Zotero, then
