ReclaiMe File Recovery is a comprehensive undelete tool which remains generally easy to use. Simply launch the program and it'll scan your system, listing all the drives and unmounted partitions it can find. All you have to do is choose the drive where your data was stored, click Start, and watch as the recovery process begins.
In our experience the program could be extremely slow, so you'll need to be patient. Thoroughness is important with undelete tools, though (no point being quick if it doesn't find your files), and at least you don't have to wait for the scanning to finish. ReclaiMe File Recovery builds a dynamic report as it goes, so you can browse an Explorer-like tree (or use a powerful search tool) to locate your missing data. Clicking a file displays a preview (if it's an image) or a raw hex view (if it's not), and once you've found your files then you can recover them in a couple of clicks.
Or, at least, you'll be able to recover them once you've paid for the program (the evaluation build lists files but won't save them). And that's where the problem comes in, because ReclaiMe File Recovery is really quite costly.
ReclaiMe File Recovery Standard can cover all file types on a Windows PC, for example, and is $79.95.
But if you want to recover files from Mac (UFS, HFS, and HFS+) and Linux (ext2, ext3, ext4, and XFS) file systems then you'll need ReclaiMe File Recovery Ultimate, which weighs in at an eye-watering $199.95.
If nothing else will do the job, then, give one of the ReclaiMe File Recovery builds a try - if it can bring back your data from the dead then you probably won't care about the price.
In general, though, there are plenty of very capable undelete tools which cost considerably less (or nothing at all), and most people will be better off exploring some of those, first.