FAT file system uses a directory entry for each file and folder. It shows starting cluster, filename, date and size. To access file, system looks in directory finds file and notes the starting cluster. Then it goes to the FAT (file allocation table) cluster that corresponds to the starting cluster. The starting cluster entry contains the cluster number of the next cluster. The next cluster entry points to the next cluster and so on until you come to an end of file marker which means this is the last cluster used by the file.
When you delete a file or folder. It locates the directory it resides in and changes the 1st letter of the file or folder name entry to E6 hex (not sure if its E6 or something slightly different) and it deletes the FAT chain.
That is why you can recover only contiguous files in FAT system once a file is deleted. All data recovery utilities will use this method. None other available unless you can find traces of the FAT with correct cluster chains still in place.