Word AutoSave replaced my chapter with an older version

Getting the newer text back

AutoSave only runs on files stored in OneDrive or SharePoint, and those services keep earlier versions of the file. Your chapter is probably there.

1. In Word for Windows, click the file name in the title bar and choose Version history, or open File › Info › Version History. Word 2016 to 2021 keep it at File › History. In Word for Mac, click the document's name in the title bar and choose Browse Version History; older Mac versions keep it under File.
2. Open the versions from around the time you last saw the good text. Each opens in its own window, apart from the file you are working in.
3. When you find it, choose Restore. If you would rather keep both, copy the text out or save that version under a new name instead.

If Word will not show the history, go to OneDrive in a browser, right-click the file, and choose Version history. Also look in the same folder for a second copy with a computer's name added to the file name: OneDrive keeps both when two devices' edits cannot be reconciled, and the missing chapter may be sitting in that one.

Why it happens, and how to avoid it

AutoSave writes whatever is open, and it does so every few seconds. A copy left open on a second computer, or reopened there from a stale cache, can be saved over the newer one before anyone notices. The fix is dull. Close Word on the first machine, wait until it reports the file as saved, and only then open the book on the other one, whether that is a desktop at work or the Word app on a tablet that has not been opened since last month.

Before an experiment, use File › Save a Copy, since with AutoSave on, the edits keep flowing into the original. And if you prefer saving deliberately, the AutoSave switch at the top left turns it off for that document.

In Tabularia

Tabularia saves every change to your device as you type, and its guide is blunt about the limit of that: autosave protects the present moment and is not a version history. The history comes from two other places. Undo/Redo History lists your edits by day, 250 steps by default and up to 500, and stays on the device that made them. A Snapshot is a restore point you take on purpose; with the Cloud plan it is backed up online.

Sync can replace text without asking here as well, and the two-device section of the guide spells out when. When whole copies of the book disagree, whichever machine reported in most recently prevails. A laptop that wakes up holding a stale copy swaps all of it for the cloud's version, and the caret lands back at the top of the book. Nor does Tabularia keep automatic versions of the book the way OneDrive does. What covers it is a Snapshot before moving to the second machine, since Snapshots are left out of that swap, and a glance at the saving indicator before you close the lid.