Word 16 suddenly would not open a document I've been working on for a while. I get the error that it needs to be recovered. After I recovered it the file contents were gibberish. My question is how do word documents become corrupt? Can this be prevented?
That's true but it can happen that people forget to close the application and turn off their computer.
Have you run sfc /scannow to check if the file system is corrupt?
You can also create a free Office accountonline and try to open that file online, see here Office 365 Login | Microsoft Office