Recovering deleted sections or pages
If you’ve deleted a page or section and want to get it back, then the Notebook Recycle Bin is your friend.
Following are the steps for restoring deleted sections or pages.
On the History tab, click the Notebook Recycle Bin button, and then select Notebook Recycle Bin from the menu that appears. OneNote displays deleted pages or sections it still has from the current notebook.
To restore a section or page, right-click the tab for the section or page, choose Move or Copy, and move it back to where you’d like it in the notebook.
If you’re sure that you don’t need anything in the Recycle Bin, you can empty it to save a little bit of space. Just click Notebook Recycle Bin on the History tab. Then select Empty Recycle Bin from the menu.