Events are completely removed from our system 6 months after the event date.
Announcements such as save the date & birth announcements are removed after 12 months of creation.
there is no way to retrieve deleted data.
If you wish to save the event's guests list prior its deletion - browse the event management page (accessed from ‘My Events’ ) and click on the 3 dots button above the guest list - then select to either print or download the list.