Types Of Hard Drive Failures.
There are really two primary forms of failure in a hard drive, logical and physical. Logical failures are usually a result of file system corruption. This can occur due to a virus, accidental deletion of key files or registry components, and in some cases even electro-static discharge. In most cases where a logical failure has occurred, the drive is still recognized by the system BIOS, but it will not boot. In most cases, your data should still be intact on the drive, even though it may appear to be inaccessible.
If the system BIOS does not detect the presence of the hard drive, then chances are a physical failure has occurred. Physical failures can result from a wide variety of causes. There are really two sub-categories for physical hard drive failures; mechanical and electronic. Mechanical failures usually result from a failure of the spindle motor. Spindle motor failure can result from excessive heat due to a bearing failure. The increased heat resulting from the bearing failure will expand the drive shaft and therefore seize the spindle motor. Suddenly, your drive will become inoperative. Occasionally, you will get a warning that something bad is about to happen. You may hear a loud whining, a grinding noise, even high-pitched screeches. If anything like this starts to occur, BACK UP YOUR DATA IMMEDIATELY.
Another physical issue that sometimes rears its ugly head is an electronic failure. If you look at a hard drive you will notice a circuit board on the bottom. This board is basically the brains of the drive, and it is where the computer interfaces to the hard drive. An electrical failure can occur unexpectedly at any time. Even brand new hard drives are not totally immune to having electrical failures. Sometimes its just a faulty component, sometimes its improper installation (i.e. electro-static discharge, grounding out the board, damaging circuitry during installation). Its important to also keep your system clean and well ventilated, since excessive heat can damage the electrical components on the drive. If you have a system that is in a somewhat contained area, you may look at adding an additional 80mm fan to cool the internal components of the system, especially the hard drive. No other component of a computer works as much as the hard drive, and therefore it is vitally important not to overlook it when cooling issues arise. A simple step like this can help against needing hard drive data recovery services...