Dear Anil,
Good day, and thanks for posting in the community.
To my understanding, your OneNote can’t sync on your iPad after updating your IOS on iPad and Mac (Ventura). Also, you cannot access your notes via OneNote giving an error code E4010690 c12qc.
If the above description of the problem is correct, for the situation you encountered we do understand the inconveniences caused and apologize for it. We understand the notes is quite important to you.
Considering, that you cannot access the notes via OneNote for web and encountered an error message, we’re afraid the issue may need to be checked and resolved from back end.
Given this, we would suggest you contact your administrator to raise a ticket from Microsoft 365 Admin Center and contact Microsoft 365 Online Support, as there are support engineers who are ready to help check the issue from the background. This would be the most efficient way in handling this case for you.
For reference: Get support - Microsoft 365 admin | Microsoft Learn How do I find my Microsoft 365 admin?
And for the notes which have not been synced on iPad, we suggest you copy them to other place (for example, Word document) to backup them.
Your patience and understanding are highly appreciated. Stay safe and have a nice day.
Sincerely,
John| Microsoft Community Moderator