Hi Craig,
Thanks for getting in touch!
Once a user of an event is deleted, it is removed from the database almost without a trace. The entry of the ticket is deleted fromĀ wp_posts and the corresponding metadata fromĀ wp_postmeta is also deleted.
However, the WooCommerce order is not removed, so you should be able to see the order in the system. Unfortunately the ticket cannot be re-created from that order, but you can manually add a new order with the user data and the ticket to the system. This way a new ticket will be created for the user.
Hope this helps. Let me know if you have further questions.
Cheers,
Andras