When a
file is deleted from the SD card, or you format the SD card, the file is only marked as deleted on. However, as matter of fact,
the content is not deleted. Based on this point, SD card recovery software can
scan the file directory so as to find out the content the deleted file. Because
of this, it is very important not to put new files to the SD card before you
can restore the lost files. If you write any new data to the card, it will
overwrite the content of the deleted files. If so, SD card recovery software
will not be able to get lost data back.
