Recover USB Files You Thought Were Deleted, Corrupted Or Formatted

by Rod Dunne on September 20, 2010

in Data Recovery

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In terms of PC maintenance, using software to recover USB contents that you thought was deleted, formatted or corrupted is one of the simpler tasks that most people can perform. Here, we’ll step through how to use these tools and remarked on some of the things which can hinder how many documents you will actually find.

There are two important facts which make it possible to recover USB files. The first is that a deleted file is never immediately wiped from the USB memory. It is only the index or address that is removed, but the document’s contents still remain intact as data clusters on the Flash memory.

Secondly Flash memory uses the fat 32 file system format, which is the same one used for Windows operating systems and internal hard drives. The benefit of this is that recovery applications which depend upon understanding the file system format are plentiful for the Windows fat 32 system and can therefore work on internal hard drives and USB Flash devices.

Using software to recover USB Flash data.

When it comes to data recovery USB devices are just as simple to find data on as internal hard drives. First download and install a file recovery application of your choosing. Some suggested applications to try are Remo Undelete.

  1. Start up the application.
  2. Choose the USB drive/directory for analysis.
  3. The file recovery tool will then the scan the Flash memory for data clusters. A list of found clusters/documents are compiled and presented back to you.
  4. Pick the ones you want and copy them to a new location.

Factors affecting data recovery

When a file has been deleted or formatted then its clusters are not immediately wiped from the memory. However, the clusters are flagged as available to reuse for saving new files. This means that in due course these clusters will be overwritten with any new data. So, the best results are achieved if you try to recover deleted files immediately after a document have been deleted or formatted.

For formatted Flash devices, there is an extra complexity to consider. The formatting process will clear down the file allocation table (FAT) of all document indexes. The FAT file stores these file indexes along with the addresses of all the clusters associated with the document. Format recovery tools recover USB Flash data by using the file allocation table to reassemble clusters into well formed files. When formatting has cleared down the FAT file, then the software has to use its own logic to reassemble documents. As each program will do this differently, there is the potential that each program will find a different selection of files. See our guide on how to recover formatted hard drive data for details of tips and software tools to use for retrieving formatted documents.

Finally, trying to recover files after format is made impossible if the formatting process also include a data cleaning or cleansing pass of the Flash memory (for data protection/evidence wiping when selling your PC/USB device) then this will effectively clear all clusters from the memory resulting in the loss of your data. While data recovery experts do sometimes claim that their advanced forensic software can still retrieve files in this scenario, this could be a costly process to pursue.

Our article on how to recover overwritten file contents provides more information about retrieving lost files you suspect have been overwritten.

Recover USB files on damaged devices.

An important factor of any file recovery software is the fact that it needs to be able to read the memory in the first place. You cannot recover USB data if the USB device has been water damaged, broken or has some other form of component damage that will stop the successful reading of Flash memory. In the event of this happening, you could resort to using data recovery experts who can read the Flash memory directly using specialist tools. Be warned though, this can cost hundreds of dollars to do.

Related posts:
- A basic guide to using software to restore deleted files.

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