File information=Files Directory + Data Field.
If any damage occurred in the file directory or the data field, it would be difficult to preview or open the recovered files.
If files directory and Data Field are intact, data recovery tools will easily recover the lost files by searching File Directory of the partition and the recovered files will have original file names and folder structures.
But if the file directory is corrupted by some changes (reformatting, system reinstallation, partition/drive show as Raw Status or other changes, etc), the Files Directory cannot point to the right Data Content. So in this case, the data recovery tool cannot find valid data by searching File Directory. That the reason why you cannot find the lost file with original files name and folder structures. Or the recovered files have original file names and folder structures but cannot be opened.