If you're reading this article, the good news is that the data is likely still there under the hood. To retrieve your data, follow this workflow:
Add the fields you removed from the ticket field back to the ticket.
Refresh the event page. The data should be there.
If you have some cleanup work to do and need to grab all of the data, don't forget that you can download the list to a CSV.
Checkout this article on how to safely change the fields on an event ticket.