How do I undo a mistake I made yesterday?

First, protect today's work

Before restoring anything, save a copy of the manuscript exactly as it is now. The trap in any rescue is rolling the whole book back to yesterday and losing this morning's good pages along with the bad cut. The safer habit is to open the old version on its own, copy out the passage you need, and paste it into today's file.

In Google Docs

Open Last edit, in the top right corner of the document, or choose File → Version history → See version history. Versions are listed by time, and selecting one shows who changed what. Pick one from yesterday and read it. Copying text straight out of it works. If you want that entire version back, Restore this version does it. Name today's version first, with More → Name this version, so it is easy to find again. The same More menu offers Make a copy, which is the gentlest route of all.

In Word, and in Scrivener

Word's undo list ends when the document closes. Yesterday has to come from a saved version. Where to look depends on where the file lives:

• OneDrive or SharePoint: click the title of the file in Word's title bar and pick Version history, or Browse Version History on a Mac. Older releases keep it under File. Open yesterday's version. Copy from it.
• A backup copy: if Always create backup copy was switched on in Word's options (on Windows, the Save section of Advanced), a file named Backup of … sits beside the original, holding the previous save.
• The computer's own backups: right-click the file and look for Restore previous versions on Windows (it depends on File History being on), or use Time Machine on a Mac.
• Sync services: Dropbox keeps earlier versions of a file for 30 days or longer, depending on the plan. Google Drive drops a version after 30 days or 100 newer ones, unless you mark it Keep forever. iCloud Drive is different: iCloud.com recovers files deleted in the last 30 days, and Apple's instructions there cover deleted files rather than earlier versions.

In Scrivener, a snapshot taken before the change can be compared and rolled back from the Snapshots pane of the Inspector. Without one, Scrivener's automatic backups are copies of the project, usually zipped; the Backup settings show where they are kept. Unzip one to a new place, open it beside the current project, and copy the text across.

In Tabularia

Open the project's History and switch to Undo/Redo History. It groups edits under Today, Last 7 days, and then one row per earlier working day, with each edit's change in word count. Selecting an entry takes the manuscript back to that point. If you took a snapshot, Preview reads it onto the page without changing your wording, and Restore snapshot first saves where you stand as Before Snapshot restore. Take a snapshot of today before stepping back either way.

Its limits are real:

• A project keeps 250 undo steps by default, 500 at most. A long day of editing can push yesterday past the edge; snapshots do not expire that way.
• Undo/Redo History stays on the device that made it, even with Cloud sync. Snapshots back up with a Cloud subscription.
• Restoring a snapshot applies to the whole manuscript, and it discards unresolved review changes and any comments added or changed since. The dialog counts them before you confirm.