What is Data Recovery

Data recovery is the process of extracting data from damaged, failed, corrupted, or inaccessible secondary storage media when it cannot be accessed normally. Often the data are being salvaged from storage media formats such as hard disk drives, storage tapes, CDs, DVDs, RAID, and other electronics. Recovery may be required due to physical damage to the storage device or logical damage to the file system that prevents it from being mounted by the host operating system. Although there is some confusion as to the term, data recovery can also be the process of retrieving and securing deleted information from a storage media for forensic purposes or spying.

taken from http://en.wikipedia.org