Hey there!
Nice to meet you! I'm Randy, an Independent Advisor.
Hi Jean, that message means the file might be corrupted or saved in a newer format your Word can’t read. That’s why it looks like gibberish when you open it.
Try this: save the file to your computer first, then open it using Word or go to office.com and try Word Online.
This can also happen if the file came from email or OneDrive and didn’t upload or download properly.
Best regards,