"What are the reasons for failure Hard Disc Drive"
Sometimes it just happens. The manufacturing process is not perfect for any computer component, and sometimes, you just get bad drive, even right out of the box. Usually in a case like that, it is electronic in nature, but in your case, since you have had it for a while, it sounds physical. Electronic problems, especially as time goes by, are usually related to inconsistent power...spikes in power and brown outs, either of which is not particularly good for a drive.
Typically, when a person has a physical problem, it is also due to power. This often leads to what was called a "head crash", which when the computer lost power, the heads often hit the platters causing physical damage. I actually thought that most modern drives had addressed this problem, but not according to the following article, although some have. Any Superuser users' comments regarding this would be welcome. Of course, sometimes people drop or bump drive, especially in laptops. This can also render a drive unusable.
http://en.wikipedia.org/wiki/Head_crash
The the best of my knowledge, a virus cannot physically harm a drive. I have had viruses that just could not be found, but I knew were hidden in the boot sector areas, and could only be removed by a low-level format (a utility that writes all zeros to the drive), and then doing a standard format, but no physical damage. For those who know more than me about disks, I realize that if I knew more about disk editing, I could have done that instead, but editing it directly was not an option for me.