Restore files to a page that no longer exists

If the page where deleted attachments originally existed is deleted, the attachments are still recoverable.

On the Expert toolbar, navigate to Site tools > Control panel.
In the Control panel, under Maintenance & History, select the Deleted Files link to view the deleted file.
If the original page of a file was deleted, the Original location column displays ~~Deleted page~~.
Select the checkbox of the file and click Restore file.
When the file is restored, a placeholder page of the original page is created without content but with the restored file attached.
From the Attachments list, you can move the file to another page by selecting the move icon.