I installed Calibre. I did nothing. All the images in a critical Word file were replaced with an image number. It did it to every file on the computer, including my backup file for protection.

Please tell me how to reverse this.

Is there any actual support for Calibre?
It seems more likely to me that you moved the folder containing the images somewhere. (It sounds like the images in the word file were only references to the location of the actual images.)