There are 4 main types of hard disk failure, often the most serious by far is a mechanical fault.

Mechanical faults are frequently caused by the hard drive being dropped or receiving a knock. This is turn damages the drive’s read/write heads – the parts that interact with the disk’s surface and transfer the data from the hard drive into the memory of the computer. The give away symptom of a mechanical fault is that the drive will make a knocking or ticking noise when it is powered on and not be recognised by the computer.

In order to recover the data from the hard drive it’s often necessary to replace the damaged heads with new identical ones. This requires a clean room and a high degree of technical ability.

Listen to the sound made by a hard disk drive with a mechanical head fault

For more information on the main categories of hard disk drive failure you can visit this page.