TestDisk is OpenSource software and is licensed under the terms of the GNU General Public License (GPL).
TestDisk is a powerfull FREE data recovery tool it can run under windows as well as Linux.
Here's what their site says,
* Fix partition table, recover deleted partition
* Recover FAT32 boot sector from its backup
* Rebuild FAT12/FAT16/FAT32 boot sector
* Fix FAT tables
* Rebuild NTFS boot sector
* Recover NTFS boot sector from its backup
* Fix MFT using MFT mirror
* Locate ext2/ext3 Backup SuperBlock
* Undelete files from FAT, NTFS and ext2 filesystem
* Copy files from deleted FAT, NTFS and ext2/ext3 partitions.
Technically you can recover all your lost data if only if you have not written over the recovering data.
To know more about TestDisk visit their site: http://www.cgsecurity.org/wiki/TestDisk
Step by step tutorial of TestDisk http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step