The four most common reasons for data loss are: Deletion. You deleted the file by accident during a disk cleanup, or because you thought it was no longer required.Overwriting. You saved a new file over the top of the old one. However, the old data may still exist, and be recoverable.File system corruption. The disk suddenly appears empty, or the file and folder names contain gibberish. Physical damage or hardware failure. You receive error messages when you try to read the disk, or it is not recognised by the computer at all.

In each case, there is a good chance that the data still exists.The Data recovery tools use different methods to try to recover data. Some tools are designed for recovering deleted files, others are better at restoring overwritten files, or recovering files from disks that are physically damaged. Some data recovery software products have been developed specifically for recovering photo images, or Microsoft Word or Excel document files. Such products may succeed where others fail because they understand what these files look like, and can recognise their data when other clues to its existence have vanished.