My draft disappeared from my notes app

Evernote

Search every notebook for a phrase you remember, then check Trash. If the note is there but its text is older than it should be, open it and look for Note history in the note's ⋯ menu. Evernote documents it for the desktop and web apps, not the phone app.

When two devices edit the same note before syncing, current versions of Evernote may keep the other side as a second copy of the note, so search for the title and look for a duplicate. Older versions filed those copies in a separate notebook with Conflicting Changes in its name. If your account still has one, open it too.

OneNote

• Deleted pages and sections go to the notebook's recycle bin: in the desktop app, History › Notebook Recycle Bin.
• Overwritten text may survive as an older page version: History › Page Versions.
• Sections OneNote could not sync because it lost track of their files are gathered under Misplaced Sections in the notebook list, where you can move them back.
• Local backups, if the desktop app kept them, open from File › Info › Open Backups.

Menus differ between the Windows desktop app, the Mac app, and OneNote on the web.

Apple Notes

Deleted iCloud notes sit in Recently Deleted for 30 days. Here is the catch. Each account keeps its own folders. Notes can live in iCloud, on the device only, or in a mail account like Gmail, and a note in one of those never appears in another's Recently Deleted. Tap back to the folder list and look under every account heading. A note deleted from a mail account usually lands in that account's Trash in the Mail app instead, and Apple's advice is to copy it from there into a new note.

If a whole account's notes vanished, check that Notes is still switched on for that account under Settings › Apps › Notes › Notes Accounts. Signing out of iCloud, or turning Notes off for it, removes iCloud notes from the device without deleting them; they remain at iCloud.com, which has its own Recently Deleted folder.

In Tabularia

A notes app holds a thousand small things; a novel needs fewer, sturdier ones. In Tabularia the book is one manuscript, so there is no loose note for a chapter to slip into. Alternative versions are Drafts, and deleting a Draft files it under Archived with its wording intact, where Unarchive brings it back.

For the book as a whole, Snapshots are the restore points and Undo/Redo History the day-by-day record. Neither is a guarantee. On the Free plan everything lives in one browser, and with the Cloud plan, archiving or deleting a manuscript on one device does the same on the others. The guide on sync, backup, and offline sets out both.