Hello Damien,
Thanks for reaching out to Microsoft Q&A forum Support.
I understand that you voluntarily deleted all content from your OneDrive, emptied the trash, and reinstalled your operating system, only to discover that your OneNote notebooks were also deleted and not restored when you attempted to roll back OneDrive.
It is important to note deleting OneNote notebooks from OneDrive and emptying the recycle bin permanently removes them, and restoring OneDrive to a previous date often fails to recover manually deleted files especially if they weren’t stored in the “My files” section.
Here are some of the recovery options:
- Check OneNote’s Built-In Recycle Bin
- Open OneNote (desktop or web).
- Go to the View tab.
- Click Deleted Notes.
- If you see your deleted content, right-click and choose Move or Copy to restore it. Recover deleted Notes
- Restore from OneNote Backups: OneNote automatically creates backups.
- Open OneNote.
- Go to File > Info > Open Backups.
- Browse through available backups and restore the notebook or section you need.
Best wishes,
Maryam | Microsoft Q&A Support Moderator