Retrieving registration data from rescheduled Zoom webinar

I was editing the description of a Zoom webinar series, and somehow it rescheduled some of the instances to create a regular series (i.e. first Thurs of the month) instead of the dates I can previously selected. Hundreds of registrants received an automatic email that the webinar had been rescheduled, and were unregistered for the webinar. When I updated the dates back to the original, all the registration data seems to have been lost.

How can I retrieve the previous registration data from the rescheduled webinars?