I have similar .odt files of about 25 KB each in the folder pictured below, each file containing no more than 16 pages of text (no pictures or other objects).
However, there is one .odt that is greatly larger in size at 154 KB, yet it was created as only a few pages of typing, just like the others. It should only be 20-odd KB.

When I open it, I now get a dialogue box that does not appear when I open the others (I have tried many different combinations of Character Sets, Fonts, and the Paragraph Breaks to no avail).

The file is now ballooned to a huge 625 page document of only symbols and gibberish. My original 5 or 6 pages is gone.

Is there anything I can do to get back my typing?
TIA for any ideas