To recover a deleted page (or blog post, etc.), go to Tools > Versions in the Elefant admin toolbar.
By default, Versions shows a list of pages, but you can choose from other types of content in the Type drop-down menu.
From here you'll see a list of items (e.g., pages) in reverse chronological order. Find the item you want to restore and click Show versions in the right-most column.
This will bring you to a list of versions of the item, each of which you can click to Compare to current or in the case of the current version, you can click View current to view it.
In the comparison screen, there will be a link under the left-most version to Restore it. Click that to finish recovering the deleted item.