Short answer: NotebookLM has no undo for deleted notebooks or sources, and deleted content does not sit in a trash folder you can dig through. If you did not export a backup before the deletion, the content is almost certainly gone. If you did, you can import that backup into a fresh notebook with NotebookLM Tools and recover the source list.

This guide is honest about both sides: what is actually recoverable, and how to set up a per-notebook Backup & Restore habit so the next accident is a non-event.

What Can and Cannot Be Recovered

NotebookLM does not offer a trash bin, version history, or per-source undo. Once you confirm a deletion, the content leaves your notebook immediately. There is no hidden Drive folder where deleted notebooks reappear and no third-party service that can pull them back.

What this means in practice:

Deleted notebooks — unrecoverable by any tool unless you exported a Backup & Restore file beforehand. If you did, you can rebuild the source list into a new notebook.
Deleted sources within a notebook — same story. Removing a source from a notebook is immediate and final. The extension cannot reach back into NotebookLM and retrieve it.
Deleted chats — not recoverable.
Deleted studio items (audio overviews, mind maps, reports) — not recoverable.

The honest framing is that "recovery" in NotebookLM really means "restore from a backup you already made." There is no other path. If that backup doesn't exist, the work is gone.

If You Have a Prior Backup: How to Restore

NotebookLM Tools ships a per-notebook Backup & Restore dialog. If you previously exported a notebook to .json or .zip, you can bring those sources back into a new notebook:

Open NotebookLM and create a new, empty notebook.
Click the NotebookLM Tools extension icon to open its panel.
Open Backup & Restore and switch to the Import Backup tab.
Select your .json or .zip file. The dialog shows a preview (original notebook title, source count, export timestamp for JSON; filename for ZIP).
Click Import Backup. The extension adds each saved source to the current notebook one by one. Import is additive — it does not overwrite or delete anything already in the notebook.

What you get back from a JSON backup: notebook title and emoji metadata, every source's title and URL, the full content of each source, and the source folder organization.

What you get back from a ZIP backup: each source as a separate .md file (filename index-title.md) with the original URL included as a blockquote. Folder organization is not included in ZIP — use JSON if you want folders preserved.

What you do not get back, regardless of format: chat history and studio items (audio overviews, mind maps, reports). NotebookLM does not expose those for export, so no extension can back them up. If a specific chat thread matters, copy it into a note inside the notebook before you make risky changes — notes travel with the notebook.

If the Restore Creates Duplicates

If you import a backup into a notebook that already has sources, you will end up with duplicates. NotebookLM Tools includes a Duplicate Scanner for exactly this case:

Fast scan — matches by source title and URL. Quick and covers most realistic duplicates from a re-import.
Deep scan — compares content similarity. Slower, but catches duplicates with different titles but overlapping content (for example the same article saved from two URLs).

Run the fast scan first. Use the deep scan if you suspect silent duplicates after merging or re-importing.

If You Have No Backup

Be direct with yourself here: if you deleted a notebook or source and never exported a backup, NotebookLM Tools cannot recover it, and neither can any other extension, script, or third-party service. The content is not sitting in a hidden folder waiting to be pulled back. It is gone.

The narrow partial-recovery paths that sometimes help:

If the source was a Google Drive file — the original file may still exist in Drive. You can re-add it as a new source in NotebookLM. You lose anything that depended on the old source ID (such as citations in prior chats), but the content returns.
If it was a web URL or YouTube video — check your browser history for the URL and re-add it through the normal Add Source flow or via the right-click import.
If it was pasted text or an uploaded PDF with no external copy — it cannot be recovered.

That's the complete honest list. Anything beyond this is wishful thinking.

Prevention: The Only Thing That Actually Works

The right time to plan recovery is before the deletion. The workflow that actually works:

Export a backup before any destructive action. Before bulk-deleting sources, merging notebooks, or reorganizing a folder structure, open Backup & Restore and export the current notebook as JSON. It takes a few seconds.
Pick the format that matches your need. JSON preserves folders and full metadata — use it for notebooks you might need to rebuild. ZIP gives you one Markdown file per source — useful if you also want the content outside NotebookLM.
Keep the backup somewhere persistent. A synced folder (iCloud, Dropbox, Drive) or a git repo works fine. One backup per major milestone is enough for most notebooks.
Back up on a cadence for active notebooks. Monthly is a reasonable baseline. Weekly if the notebook is changing daily.
Run the Duplicate Scanner after large imports. Catching duplicates early keeps later cleanups simpler.

Full walkthrough in NotebookLM Tips #6: Backup and Restore.

Frequently Asked Questions

Can NotebookLM Tools recover a notebook I deleted without a backup?

No. Without a prior .json or .zip export, there is no way for the extension — or any tool — to reach back into NotebookLM and retrieve deleted content. The extension only imports from files you have already saved locally.

I removed a source from my notebook by accident. Can I undo it?

NotebookLM has no undo for source removal. If you have a prior backup, import it into the notebook and the source returns (the import is additive, so your other sources are untouched). If the source was a Google Drive file, web URL, or YouTube video, you can usually re-add it from the original location. Pasted text or uploaded PDFs with no external copy are not recoverable without a backup.

Does NotebookLM have a trash or version history?

No. Deletions are immediate and final inside NotebookLM. This is the central reason a separate Backup & Restore workflow matters.

Will a backup restore my chat history and audio overviews?

No. Backups cover the source list only — titles, URLs, content, and folder structure. Chats and studio items (audio overviews, mind maps, reports) are not exportable, so no tool can back them up. Copy important chat outputs into notes inside the notebook if you want them preserved.

How often should I back up?

Before any destructive action, always. For active notebooks, a monthly cadence is sensible; weekly if you edit the notebook daily. Exports are small and take seconds.

What is the difference between JSON and ZIP export?

JSON contains notebook metadata, every source's title and URL, the full content of each source, and the folder organization — it is the format to use if you might need to rebuild the notebook. ZIP produces one .md file per source (filename index-title.md) with the URL as a blockquote; folders are not preserved. ZIP is more useful when you want the content outside NotebookLM.

Can I recover a shared notebook if the owner deleted it?

If you are a collaborator and the owner deletes the notebook, you lose access at the same moment. Only the owner can restore it — and only if they had exported a backup beforehand. Without that backup, the notebook is gone for everyone.

The Practical Fix: Back Up First

There is no trash bin or undo inside NotebookLM, and no third-party tool can recover what you haven't already saved. A periodic per-notebook Backup & Restore export is the only reliable insurance. NotebookLM Tools handles the export and the import; see the backup and restore feature.

Related articles:

NotebookLM Tips #6: Backup and Restore — Full walkthrough of the backup workflow this guide relies on.
Can You Merge Notebooks in NotebookLM? Here's the Workaround — Consolidate notebooks safely using backups as a checkpoint.
How to Organize NotebookLM Sources with Folders — Reduce accidental deletion with clearer source structure.