OneNote section disappeared upon logging in

Hello @Porsche Vass,  

Good day! Thank you for posting your valuable question on Microsoft Q&A forum.   

To help us provide the most accurate and effective solution for your missing section, could you share a bit more detail about your setup? 

• Which OneNote version are you using? (OneNote for Windows 10, OneNote 2016, OneNote Online, or mobile app?) 
• Are you signed in with a personal Microsoft account (e.g., Outlook.com) or a work/school account linked to your organization’s domain? 
• Do you see the missing section on any other device or in other OneNote platforms (desktop app, web version, mobile apps,…)? 
• Was the section created recently or has it existed for a long time? Did you make any changes before it disappeared (e.g., renaming, moving, or sharing the notebook)? 
• What operating system are you using?  (Windows, macOS, iOS, Android?) 
• As you said you check the History, have you also checked OneDrive’s Version History for the notebook file? 
• Do other sections in the same notebook appear correctly?  (This helps determine if the issue is isolated or notebook-wide.) 

This additional context will help us understand your environment and the steps already taken so we can tailor the guidance to resolve the issue effectively. 

In the meantime, here are some basic checks you can try: 

• Make sure the section wasn’t accidentally moved to another notebook.
• View the Notebook's Sync Status and confirm that the notebook is syncing properly. If there’s an error, try forcing a sync or repairing the connection. 
• If the notebook is shared or co-authored: Ask other collaborators if they can see the missing section. Sometimes changes made by another user or sync conflicts can cause sections to disappear. 

I apologize If I could not jumping straight to a solution. I want to avoid suggesting anything that might be inaccurate or unhelpful. Once I have the details above, I’ll be able to assist you more effectively and guide you toward the right resolution. 

Looking forward to your response so we can get this sorted out for you together.

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