I've seen this issue in the Q&A over and again. It has vexed me the past two days--and I've got a manuscript due this week to my publisher. I have tried everything, gone everywhere searching, but . . .
SOLUTION FOUND!
I use a stand-alone copy of Word (not the stupid useless web version). I found out I had likely inadvertently clicked the "VIEW" "WEB LAYOUT" button. All 70 pages turned into a 1-page document.
I chose "view" and "print layout" and the pagination all returned!!!
Just hoping this helps anyone with the same issue.
https://www.google.com/search?q=where+did+my+page+breaks+in+word+go&rlz=1C1GCEA_enUS1120US1120&oq=where+did+my+page+breaks+in+word+go&gs_lcrp=EgZjaHJvbWUyBggAEEUYQDIICAEQABgWGB4yCAgCEAAYFhgeMg0IAxAAGIYDGIAEGIoFMg0IBBAAGIYDGIAEGIoFMg0IBRAAGIYDGIAEGIoFMgoIBhAAGIAEGKIEMgoIBxAAGIAEGKIEMgoICBAAGIAEGKIEMgcICRAAGO8F0gEINzg0N2owajSoAgCwAgE&sourceid=chrome&source=chrome.ob&ie=UTF-8
Solution NOT found here on Microsoft anywhere.