How can I recover a document I deleted?
Once you delete a document, it is completely removed from your phone. There is no concept of Trash in Genius Scan.
If you deleted a really important document, your only way to recover it would be to restore a backup of your entire phone from before the accidental deletion. This is only possible if the last backup of your phone happened before the deletion. This would also erase any change, SMS, settings etc. of your phone since that last backup.