Note: This review addresses v1.38 of the software.
Chances are that if you've accidentally erased a file, or something malicious like a worm or virus has done it for you, Recuva will find it. It's a great little undelete program, possibly the best on the market... if you can really say donationware's on the market. Also, Recuva is the only free/donationware sector-based recovery software that I've found.
Recuva's sector-based recovry worked for me on a number of occasions, but it doesn't support SCSI--and once or twice in previous versions failed to find files. This version seems effective, so if your hard drive's health is stable, it's worth a try in that role as well--and could save you quite a bit of cash. Unless I'm absolutely sure a hard drive isn't degrading during further use, I use tried and true R-Studio Data Recovery.
Recuva has a nice-looking, simple interface as well as a wizard that will walk you through the recovery/undelete process. There are options for what type of files to search for as well as whether to enable the deep scan (sector scan) that will find files on damaged or reformatted disks.
If you just want a good un-delete program with a small disk footprint at no charge, then Recuva is what you're looking for. It's also worth a shot at recovering overwritten or damaged data on an otherwise healthy hard drive. It works on both FAT and NTFS file systems so you can undelete files on virtually any Windows PC ever made, and the interface is the very model of restrained style and efficiency.
Note: This program is donationware. It is free to try, but the author accepts and encourages donations towards further development.
--Jon L. Jacobi