If you delete a property in a Notion database, it’s possible to restore that property. Follow these steps to do so.
First, ensure the database is unlocked. Check out this article to learn how to unlock Notion databases: How to Unlock Notion Databases
Once done, open the database’s settings using the three-dot menu in any view. Navigate to the Properties menu:
Within Properties, scroll to the very bottom and find Deleted Properties.
Within Deleted Properties, you’ll see a small ↩︎ icon next to any properties that have been deleted. Click it to restore the deleted property.
Once restored, the property should show up in all its previous locations within your workspace, and property values on individual database records should be restored as well.
After performing this restoration, I recommend re-locking your database! The re-locking process is described near the end of this article: How to Unlock Notion Databases