A web-based tool in Microsoft 365 that enables users to quickly create surveys, quizzes, polls, and feedback forms.
Based on my testing in my environment, I created a test webinar, allowed it to complete, and then cancelled it afterward. Even after cancelling the webinar, I was still able to access the webinar chat, as well as the Recap and Attendance tabs.
Could you please check whether the webinar is still available in your Teams chat? If so, please open the webinar and check the Recap and Attendance tabs to see whether the recording and attendance information are still available.
If the webinar chat is no longer available, you may also check whether the recording is still available in the organizer's OneDrive or SharePoint.
For the attendance report, if the webinar chat is no longer available, I’m not aware of an alternative way to access or retrieve the report.
If the recording is not available in Teams, OneDrive, or SharePoint, unfortunately, there may not be another way to recover it after the webinar has been cancelled.
I hope this helps, and I hope you’re able to recover the recording and attendance information you need.