Do you mean that you stored a Word file in Zotero itself, and then renamed it outside of Zotero, and then tried to open it? That would cause Zotero not to be able to find the file, and it would download the last version that had been uploaded to the online library. And when it downloads a file, it deletes any other files that exist in the storage subfolder, which in this case would include the renamed file. So I'm afraid if you don't have another backup of the file, that version is gone.

If you need to rename a file, you can click the title at the top of the item pane after clicking on the attachment, which allows Zotero to continue tracking it.

We can consider showing a warning if 1) a file can't be found, 2) the file is available online, and 3) there's a file with a different name in the same storage subfolder, asking which file you want to keep. But the storage folder is really meant to be managed by Zotero, and it doesn't expect changes to be made from outside.

You can try some undelete tool for your OS, but other than that, I’m afraid not, sorry.