Recoverability of the FAT (including FAT32) file systems is poor due to their
inherent structure. The NTFS (NT File System) is highly recoverable and this
discussion does not apply.
As a quick summary:
Deleted or corrupted FAT volumes: highly recoverable.
Reformatted FAT volumes: poorly recoverable.
Accidentally deleted files: recoverable only if contiguous.
Contiguous versus fragmented files
A contiguous file is stored on one segment of contiguous disk clusters. A fragmented file is stored
on multiple disjointed segments, linked together via the File Allocation Tables (FATs).
A file is usually contiguous when first created but becomes fragmented when edited. Static files
such as picture files, program executable files, read-only PDF files, MP3
files, etc. are usually never modified and remain contiguous. Dynamic files
such as email folders, Microsoft Office documents, database files, etc. are
routinely edited and quickly become fragmented.
Fragmented files can become contiguous when a disk is defragmented using the Windows Disk
Defragmenter. However, a disk should not be defragmented after data is
already lost. Doing so can only worsen the situation.
The first segment can usually be located. Contiguous files only have one segment and can be recovered
without the FATs. Fragmented files need the FATs so that subsequent segments
can be located.
Deleted or corrupted FAT volumes: FATs are intact and files are highly recoverable.
Reformatted FAT volumes: FATs are reinitialized therefore files are poorly recoverable.
Accidentally deleted files: FAT entries for files are reset; therefore only contiguous files are recoverable.
Note that when a volume is reformatted with a different file system, recoverability is mostly determined
by the original file system.