There are a few scenarios in which in which your data seems to be lost but a data recovery program can recover all or most of the lost files.
Probably the most common situation when you would want to try and recover data is from a failed, damaged or inaccessible storage device. This could be anything from an Ipod or CD to your computers hard drive. In most cases is preventing you from access your data is damage to the file system that categories and organizes your files but the actual data itself still exists on the storage device. Data recovery programs override the damaged file system and directly access the existing data on the device.
Another very common scenario is the recovery of “deleted” files. When you delete something on your computer or mobile storage device the file itself is not actually deleted just the reference to the file. The space on the hard drive where the file is written is then made available but still exists until it is actually over written by a new file. Whether it is an email, image or important file it will typically remain on your hard drive for some period of time and a data recovery program can scour all of the recorded data and recover the files you are looking for.
The other situation when you would likely want to try to recovery data is after a permanent hard disk failure, is this situation the data cannot be easily read. However there is still a chance all or some of data can still be recovered with the right data recovery program.
If you computer has crashed and you fear that you have lost all your data like pictures and word documents there is still hope. Often when a computer crashes the data is still intact on the hard drive and a data recovery program will allow you to recover this precious information.