TestDisk is a free data recovery utility. Usually associated with Photorec
TestDisk is powerful free data recovery software!
It was primarily designed to help recover lost partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software, certain types of viruses or human error (such as accidentally deleting a Partition Table).
bib ref : http://www.cgsecurity.org/wiki/TestDisk