PC owners can now store massive volumes of data on their USB Flash drives and external/internal hard drives. The first line of defense for this data should always be to have a back-up process in place from which you can restore data. This article looks at the options open to you when back-up copies are not available and you have to look into hard drive data recovery.

There are a couple of important technical points to understand about deleted or lost data on any drives:

  • Deleted files are not lost forever. All files have an attribute relating to what folder they belongs to (e.g. the 'My Documents' folder). When a file is deleted, this attribute is cleared and Windows de-indexes it. The data still exists on the drive/Flash memory but the Windows user interface will not show the file appearing in any of its folder. The section of data on the drive is now available for use at a later stage but the device driver probably will not overwrite the data while there are empty data sections on the drive.
  • Flash memory and external drives are treated by Windows in the same way as internal hard drives. They are all FAT formatted so hard drive data recovery software will also work on USB keys and external disks.
For data that has been accidentally deleted the first place to check is the Recycle Bin for the device. If the file is present then you can select it and hit restore to move the file back to its previous location.

If you need to recover deleted files that are not appearing in the bin then you will need to use data recovery software. There are commercial and free ones widely available online – just go for one with plenty of good customer reviews. All these tools scan the drives for files where the folder attribute (see above) has been cleared and displays these files back to you. The same scan should work on external drives, Flash memory drives and internal drives.

Recovering data from Flash memory can even be done when the drive is corrupted as any faults may only affect sections of the chip. Using software, the healthy sections of the USB Flash can still be scanned for data to retrieve.

It should also be possible to scan & find data on a formatted hard drive or USB key as the formatting may only remove the folder indexes of any data present. The one exception where data will be lost for good is if the formatting software has used some form of iterative deletion/cleaning process that repeatedly writes trivial data to a formatted drive in order to completely overwrite the drive's data.