Office 365, OneDrive and OneNote file recovery options
Microsoft OneDrive has a few options for recovering deleted files
OneDrive File Recovery Options
Microsoft's OneDrive application has a few options for recovering data. One option is to retrieve items from the OneDrive recycle bin. The other option is to restore your OneDrive contents to a previous time. Both options are detailed in Microsoft support documentation.
OneNote documents in the cloud are saved in the user's OneDrive. In the event a user cannot find their Notebooks, please have the user check their OneDrive and additionally use the options below if they are missing.
Otherwise OneNote notebooks can also be saved Locally into a user's device depending on the App version of OneNote. The user will need to also manually search their own device in the event of lost Notebooks. The OneNote file extension to search for is .one