When you accidentally delete a file or find out that you have been a victim of a malicious virus attack that has deleted critical files, the first thing you have to do is not to create any new files or edit any existing files. By refraining from any further creation of data files dramatically increases the chances of you being able to recover a deleted file. Running a disk de-fragmentation application will destroy your deleted files. If you are running windows and have scheduled the Windows diaphragms tool to run then you should immediately switch of the scheduled de-fragmentation run until you have recovered the required deleted files. Most of the deleted file recovery utilities are not limited to just recovering data from hard disks, but can deal with files deleted from memory sticks, USB flash drives and other removable data drives.
How Disk Recovery Programs Work
To get the best of software utilities that recover deleted files you must have an understanding of how a computer stores files. The file management system of a computer consists of two parts. One part is used to store the data and the other part of the disk is employed to store information that maps where the data is located on the storage media in an index table. When files are deleted the operating system simply marks the relevant portions of the index table corresponding to the deleted file as free to be reused. The actual data is never removed but just overwritten either by a new file or the update of existing files This is why it is important never to create new files or update existing files once you realise that you have deleted a file and wish to recover it. File recovery programs employ sophisticated algorithms that scan the storage media to rebuild the index table to recover deleted files.