Thanks, Jeanette. I just had a hard drive failure too. I think it helped me to really appreciate all the articles I'd written insisting on the importance of regular backups. I wish I read what I wrote.
Viruses can't actually damage hardware. They can wreck your boot sector and partition information, which effectively destroys your data. Viruses are computer terrorism without a cause.
You can tell some things by ear. Listen when you turn the machine on. You should hear the drive spin up, a rising note like the Jupiter II sometimes made if the Space family Robinson ever scored any Deutronium or whatever the stuff was that fuelled it and succeeded in taking off.
When the drive has spun up, you should hear a sound like tiny ball bearings dropping into the little eyes in one of those frustrating plastic games. This, I believe, is the head positioning.
Then, of course, comes the chuckling, chattering sound like millions of tiny typewriters that is the head zipping around reading data off the disk. You'll probably see the disk light flashing if you get this far.
If you don't hear the spin up or the head positioning, you have a hardware problem.
If your problem is hardware, it might just be a controller problem. I used to get a regular failure due to an old motherboard with poor connectors. When my hard drive wouldn't boot I had to take the cover off, gently prise the IDE controller out and re-seat it. You can easily identify the IDE card because it's the card connected to the ribbon cable connected to the back of the hard drive. You can also try reconnecting the cable to the drive to possibly fix any bad contacts there.
If you disconnect the cable then become confused about which way it should go back on the drive, remember that the red wire on the blue ribbon cable is connected to pin 1, which invariably seems to be at the end of the hard drive connector next to the power connector.
Reseating the controller usually improved the contacts and allowed me to boot. Because the problem arose when I turned the computer on, I stopped switching it off.
If you get past the spin up and head positioning, but don't hear the head reading data, you may have a disk formatting problem. If you have data backup, and you can reinstall and restore all the information on the hard drive, you can try to fix that by reformatting the drive and starting again. This is a cathartic and satisfying experience when you overcome your initial trepidation. You should end up with a tidier and better organised PC than before.
However, you may well lose something, such as application configuration details that you've changed. When you back up, as you should do often, it's important to save .ini files, template files and other files that contain data you've changed. It's often hard to find out where this data resides. Sometimes it's easier to keep a log of the changes you make when setting up applications so that you can be sure of repeating them.
E-mail files are important too -- they may reside in the e-mail application directory and not be backed up with the rest of your data.
If your class wants a topic to discuss, here's one that interests me. On page 151 of our September issue we had a brief look at the question "How much does data weigh?" perhaps not as scientifically as we might have. What intrigues me is where data goes when you have a hard drive failure. It's just not there any more, is it? All those words, pictures, bits and bytes; all that work we did swapping ones with zeroes. If we think of time as a fourth dimension, our data is still happily in existence, albeit in an inaccessible stretch of the time-space continuum. There are memories left in our minds, provided that storage hasn't failed as well, and presumably there are minute disturbances in the electromagnetic field propagating outward into space that represent our data. We can't send a faster-than-light spaceship out to catch it. I suppose we can hope it might bounce back off the moon and give us a chance to decode it. My guess is that the signal would turn out to be a little too noisy. I've got the dish set up on the roof and the radio scanning the frequency bands, but on the whole it's easier to chalk it up to experience.

Jeanette wrote back:
Thanks for your very prompt reply. I think from what you have written that it was a hardware problem -- the disk spins up for 10 seconds and then dies down. I am not sorry to lose 98% of the disk -- it's the file I didn't back up that I need. We have just installed a new 2 gig hard disk -- as you say, we may end up with a better organised PC (and no more minimal installations! -- at least for a few months). I remember reading the "how much does data weigh" question with delight.
The subject has come up in class -- in particular, the temporary nature of more and more of our knowledge. I consider this to be one more comforting reason that computers will never replace the human brain. Thanks again for your prompt and thought provoking reply.

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