This Restoring Pages tutorial covers:

Finding ‘Trash’
Trash recovery period
Permanently deleting a page
Restoring a page
When you ‘Delete’ a page from the ‘Pages’ screen it is moved to the pages trash folder.

The trash feature is designed to protect you from accidentally permanently deleting content from your site. When an item is moved to the trash it is stored for 30 days before being deleted permanently.

To view a page that has been moved to the trash, from the ‘Pages’ screen click the ‘Trash’ link. If you don’t have any items in the trash, the link will not display.

Hovering over an item in the trash folder reveals an action menu. Clicking ‘Delete Permanently’ will delete the item immediately with no further recovery option. ‘Restore’ will move the item from the trash and make the post live on your site once again.