TestDisk is a 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...
TestDisk vs Disk Drill opinions
PhotoRec is file data recovery software designed to recover lost files including video, documents and archives from hard disks, CD-ROMs, and lost pictures.
DataRecovery is freeware and made by TOKIWA to undelete accidentally deleted files even from recycle bin.
The program is no longer updated since August 2013. Last version, v2.4.7, released in November 2012, can be still downloaded for free.
Data recovery program for NTFS file systems. Reads each block of the hard disk to and retrieves rebuilds file system tree on another partition.
The program is no longer updated. Last version, 0.8.6, released in June 2009, can be still downloaded from the official website.