Recovery is possible and differs based on the platform where the software is installed. I know that Polaris comes as a mobile-application, therefore the only way to recover it is if the file has been previously stored on the external storage. If that's the case, remove the SD card, attach it to PC and then use an application called Recuva to scan its contents.
Be aware that you might find applications claiming to recover files from the system partition or iOS devices. Do not trust, buy, or install them as they won't have any effect at all.