Word has a bug that could delete your document when saving it. A bug in the most recent version of the app deletes the file when you save it to your computer. The issue affects the desktop client under certain conditions and is already being investigated by Microsoft.
According to the technical support websiteWord has a bug that deletes the file after saving it. This error presented in version 2409 in all documents in Word or RTF format and deletes the file when saving a copy to the local disk. If you’ve worked for hours on a task or presentation, there’s a good chance that this problem is causing you to lose your mind.
The good news is that there is a solution and the file can be recovered by following a few steps. According to Microsoft support teamthe Word bug is activated when you save your document if the file extension is in uppercase (.DOCX, .RTF). The problem also occurs when the file includes the # symbol within the name.

How to recover file deleted by Word
If any of these conditions are met, the file will be deleted instantly when you save it. To recover it, you just have to open the recycle bin and restore it. Subsequently, you must make sure that the extension is in lower case and without special characters.
Microsoft is investigating the source of the problem. While the patch arrives to fix it, Word engineers offer some tips to prevent it from happening to you. In addition to the file name and extension recommendations, make sure to save it manually before closing. The support website notes that the failure occurs after saving when you are prompted to click “X” to close Word.
Another alternative is Check the box “Do not show Backstage view when opening or saving files with keyboard shortcuts”. This is located within Options > Keep > Don’t show Backstage view when opening or saving files with keyboard shortcuts.
File deletion is the second major bug in Word which occurs in less than three months. If we remember, an update released in mid-August caused unexpected shutdowns when writing in Word, Outlook and OneNote. The problem was related to the version of the language pack and was resolved by reinstalling it.
As on that occasion, Microsoft issued an alert and shared tips to prevent Word from crashing and losing our file. Now, engineers managed to replicate the failure and advise users to follow the instructions.