What to do when you reformat the wrong drive
The increasing use of digital cameras is making this type of error more common. You see, when you "initialize" a camera's memory, you're really formatting a solid-state hard drive. (Most cameras use utterly standard FAT16 or FAT32 disk formatting.)
People who would never reformat a PC's drive will almost surely "initialize" or reformat a digital camera's solid-state drive many times over the years they own the device. Sooner or later, almost everyone will have a reformatting.
In PCs and cameras, the trick to recover from an accidental reformat is to avoid using the drive — ideally, do nothing at all — until you can run an unformat tool. The more frequently you access the drive after an accident, the harder it may make it to get the data back.
The popular and clearly named RecoverMyFiles utility from GetData (U.S. $70) can handle both FAT and NTFS unformats. The vendor's site has more information about the program.
DiskInternals' NTFS Recovery also has a solid reputation, but it's pricey at $99. You can learn more about the utility on its page on the DiskInternals site.
The recovery may not be perfect, and you may have some manual cleanup to do afterwards, but if you haven't used the reformatted drive, there's at least a reasonable chance you'll be able to effect a useful recovery.