PhotoRec is a free program which can be used to recover most kinds of lost files - not just photo formats.
To test how effective PhotoRec is I formatted a partition with a lot of files on - then deleted the partition/drive letter.
Finally the partition was formatted again. Both times a "full" (not quick) format was performed.
After that "destruction" of the partition PhotoRec managed to recover 18631 files!
This is the procedure:
Download the TestDisk & Photorec zip file.
Extract the downloaded file to a drive/partition with enough free space for the files you expect to recover - preferably more.
NEVER place the TestDisk folder on the drive/partition that you want to recover files from.
Open X:\testdisk-6.11.3\win (X is the drive where you placed the TestDisk folder) and double click the photorec_win icon.
PhotoRec runs in a command-like window and doesn't have to be installed.
The steps (A, B, C etc) below correspond to a new PhotoRec window.
Use the keyboard's arrow keys to navigate.
A. Choose the drive you want to scan for lost files.
Then select "Proceed" and press the <Enter> key.

B. Select Intel if it's a PC, press <Enter>.

C. To scan a single partition - highlight it.
To scan the entire hard disk - highlight [Whole Disk].
To exclude file types from the scan >> select "File Opt" >> to exclude a file type: highlight it, then press "-".
Press <Enter> to return to the previous window.
Select "Search", then press <Enter> to confirm.

D. If the drive/partition was formatted with Windows - choose "Other".
For a drive/partition formatted with Linux - choose EXT2/EXT3.
Press <Enter> to confirm.

E. Choose scanning the whole drive/partition or free space only.
A free space scan should be sufficient if you deleted files by mistake and haven't used the drive/partition since.
Press <Enter> to confirm.

F. To save the recovered files in the X:\testdisk-6.10\win folder - press "Y".
PhotoRec will jump back to screen C if you press "N".

G. PhotoRec will start recovering files.
The progress can be seen in the program window.

H. Press <Enter> and quit PhotoRec.

The recovered files will unfortunately be renamed and saved in X:\testdisk-6.11.3\win\recup_dir.1 (2, 3 etc).
If you have any problems or need help please post your questions in Hardware Support

