Hi Lori,
According to your description, you are using OneNote for Windows 10.
OneNote for Windows 10 doesn't create local notebook, all notebooks are saved in online location, in OneDrive for business or personal OneDrive.
So for the first question 1) saving my current notebook online, to prevent them from losing, firstly I suggest you backup them.
You can manually copy them from OneNote client, paste them to OneNote online. You may create a new notebook in OneDrive online, paste the notes in it to save them. Or backup them in Word
documents.
For the second question 2) Finding my notebook on OneDrive, you may try following:
1.Go to OneDrive on the web, check if you can find your notebooks in
Recycle Bin, also check the Second-stage recycle bin. If yes, restore them. Please refer to
Restore deleted files or folders in OneDrive
2.Try to restore your OneDrive to a previous time. More info about this:
Restore your OneDrive
Note: we suggest you firstly backup all new items created after the date you want to restore.
Best Regards,
Tina