My Google Doc went blank. Is my novel gone?

First, rule out a display problem

A blank page is often the document failing to load, not the document being empty. Reload the tab. Try another browser, or a private window, and check that you are signed in to the account that owns the file. A book kept in document tabs deserves a look at the tab list on the left, since an empty tab can hide the ones holding the chapters.

Avoid typing into the blank page while you check. There is no reason to add a version.

Restoring from version history

1. Click Last edit at the top right of the document, which is Google's documented route into version history, or press Ctrl+Alt+Shift+H (⌘+Option+Shift+H on a Mac).
2. Versions are listed down the right, newest first. Click back until the text reappears; Expand on a grouped entry splits it into finer steps.
3. Choose Restore this version, then confirm with Restore.
4. If you would rather not touch the current state at all, use the three-dot menu on that version and choose Make a copy instead. The copy is a new document, and the original stays exactly as it was.

If the file is missing rather than blank, look in Google Drive's Trash, where deleted files wait 30 days before Drive removes them for good. A shared document the owner deleted is theirs to restore, so ask them.

Offline editing adds one caveat. Changes made without a connection are held in that browser, on that device, until it reconnects. If the missing chapter was written offline, open Docs on that same machine while online and give it time to upload. Do not clear the browser's data or sign out there first.

In Tabularia

Google records versions automatically. Tabularia does not, and it is worth being clear about the difference. Its restore points are Snapshots, and each one exists because someone pressed for it. A book with no Snapshots has none to go back to. Between them, Undo/Redo History sorts edits by day, kept locally rather than synced, and History can preview any Snapshot on the page before you commit to restoring it.

Offline behaves much the way Docs does. A device that has opened Tabularia before keeps editing and autosaving without a connection; with the Cloud plan, the new work waits in that browser until it can sync. Signing out leaves the local copy in place, though offline reopening for that account stops until the next online sign-in.