The most common failure for a hard drive is something called a head crash. A head crash is any instance where the drive head manages to touch a platter. When this happens, the magnetic media will be etched off of the platter by the head and render both the data and the drive head inoperable.
This can commonly occur if there is vibration, fast movement or sudden power off (usually a power outage) to the computer. However, hard drives do actually wear out over time (like most mechanical devices), so don’t always think that you have damaged your computer. You can generally expect this to happen after 3 to 5 years of operation.
In some instances, the data can still be recovered using specific hardware and software (which we have). The best and most reliable way to ensure that you keep your data, is to back up your important files to an external hard drive, flash drive or DVD-RW. It will save you a lot of stress in the future!