Attendee Registrations missing

We recently hosted a webinar and temporarily removed the required registration for the time the webinar was running. 

After I added the requirement again to provide it on demand, all the registration data was gone.

I can access the attendee report, but obviously I'd also be interested in the registrations as now we cannot send e-mails e.g. to those who didn't show up, to watch the recording.

Is there any way to recover the data?