15, March 2017: Learn to recover data from not detected external hard disk lost data due to not formatted, not recognized, not working,not showing up, power failure,logical damaged.
Many times, the hard disk can not be detected, not the hard disk is really bad hardware, and even partition and file system are not broken.An old internal hard drive, like a 50-year-old man in the cold winter to play basketball, he did not hurt, but he needs a long time to do warm-up exercise.
In short, if you encounter a similar problem, do not worry, do not rush to dismantle the hard drive to do hardware maintenance treatment, as is very dangerous, like desktop sometimes faulty, you only need to clean the computer dust Can solve the problem without having to spend money to find experts.
If data loss occurs, a successful recovery must ensure that the deleted data is not over-written. For this reason one should avoid all write operations to the affected storage device. This includes not starting the system to which the affected device is connected.
http://www.aidfile.com/hard-drive-recovery/how-to-recover-data-from-undetected-hard-disk.htm
Due to the extremely close spacing between the heads and the disk surface, HDDs are vulnerable to being damaged by a head crash¡ªa failure of the disk in which the head scrapes across the platter surface, often grinding away the thin magnetic film and causing data loss. Head crashes can be caused by electronic failure, a sudden power failure, physical shock, contamination of the drive's internal enclosure, wear and tear, corrosion, or poorly manufactured platters and heads.
In computing, data recovery is a process of salvaging inaccessible data from corrupted or damaged secondary storage, removable media or files, when the data they store cannot be accessed in a normal way. The data is most often salvaged from storage media such as internal or external hard disk drives (HDDs), solid-state drives (SSDs), USB flash drives, magnetic tapes, CDs, DVDs, RAID subsystems, and other electronic devices. 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 (OS).
http://www.aidfile.com/faq/recover-data-from-hard-disk-not-detected-in-bios.htm
Recovering data from physically damaged hardware can involve multiple techniques. Some damage can be repaired by replacing parts in the hard disk. This alone may make the disk usable, but there may still be logical damage. A specialized disk-imaging procedure is used to recover every readable bit from the surface. Once this image is acquired and saved on a reliable medium, the image can be safely analyzed for logical damage and will possibly allow much of the original file system to be reconstructed.
External hard disk drives are usually available as pre-assembled integrated products, but may be also assembled by combining an external enclosure (with USB or other interface) with a separately purchased drive. They are available in 2.5-inch and 3.5-inch sizes; 2.5-inch variants are typically called portable external drives, while 3.5-inch variants are referred to as desktop external drives. "Portable" drives are packaged in smaller and lighter enclosures than the "desktop" drives; additionally, "portable" drives use power provided by the USB connection, while "desktop" drives require external power bricks.
