A 16,000 word document was deleted when I tried to cancel a header

I have been working on a large document. It was approximately 146 pages and 16,000 words.
Headers shown at the page break in the larger document, prevented the entire transfer. It would only paste a portion of the highlighted text I was trying to move. It also prevented some of text from moving from the bottom of the 1st page into the next page.
I tried to remove the header I thought was the problem. Now 2/3rds of the document has disappeared.
What had been a 146 page document, became a 42 page document.
104 pages are gone and I can’t access them!
But, the word count shown at the bottom of a page still shows the original 16,000 words remain in the document. But I don’t know how to retrieve the missing text. It’s going to be very difficult to re-create this document. I need to get the text back as soon as possible. How can I fix this?

Also … I was moving text from one document from 1 file and pasting it into a different document. It was a simple - highlight section of the first document, copy it and paste it into the other document. I have been making similar transfers without problem until today. Suddenly, the paragraph section I was highlighting would not copy and it would not move to the new document. When I tried to click off of the marked section, it would extend the highlighted area further down into the next section of the document. And it would not allow it to be transferred.
Thank you for helping.

Is it possible to upload the document to a share and make available here? (Of course, save to a different name, if you haven’t saved it over your original file.)

Register at Index page • Apache OpenOffice Community Forum and ask your question there. People are helpful there and discussion is much easier than here.

When you see your document listed in your file manager, has the physical size of the document changed (in MB)? If the size has not decreased substantially, then the “missing” part might still be there, just not viewable in LO.

Try, hot keys. Ctrl + a to select all, Ctrl + c to copy all, Ctrl + n for a new document. Then right click on new document, Paste special/Unformatted Text.