Hi,

I have a PC, running Debian Lenny (5r0), that experienced an interruption of the power supply, and off course it shut down.

Since I restarted it, I'm not able to boot the computer again from the hard drive (which is the only hard drive installed on the computer).

The BIOS recognizes the HD as WDC ROM MODEL-PINNACLE.

I tried recognizing the HD myself unsuccessfully, doing the following:

• Boot the computer with GRUB, and doing the following: http://ubuntuforums.org/showthread.php?t=224351
• Boot the computer with Ultimate Boot CD, and trying to use the Super Grub Disk tool. I tried all options, and they all get stuck at some point.
• Starting a new Ubuntu installation, in order to see the partition table the installer recognizes, and the table I see is empty (I can't go forward with the installation steps.
• Boot from Ubuntu live CD, and choosing to boot from the first hard drive. I get this error message: isolinux disk error 01 ax = 0201.
  
  One more important thing to know is that before the machine crashed, it had a problem with running a kernel installation or update, complaining about some GRUB problem, if I remember correctly it was something in the time postinst script was running. MAYBE with this error message (taken from here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=477304) : User postinst hook script [update-grub] exited with value 1.
  
  What can I do further? What do you think is the problem I'm facing?
  I thought maybe there is a problem with the kernel and/or grub, after a kernel upgrade that was interrupted in the middle, and this upgrade was maybe of the same version of the running kernel, causing the machine to be unbootable. Does that sound possible? If so, What are the ways to fix such a problem?

Thanks!

Sounds like you need testdisk. Static versions of the binary are often available on the website for thewse rescue tools. It does a good job finding partitions. Just guessing, something started a write at the very start of the disk, and has overwritten the partition table.
http://ubuntuforums.org/showthread.php?t=224351#
Those instructions are for when you are fully booted, using grub from a running system.

If you ran a 'make install' on the kernel, that tries to configure lilo still, doesn't it? Grub is obviously going to be unhappy with no partitions. But try booting with an install disk for some system, hit Ctrl_Alt_F2 and you get a shell. In that, type
fdisk -l

and you will see what partitions _actually_ exist. Post that. Also take us through the exact error grub gives when you try and boot as usual.

I took the hard drive from the original computer, and reconnected it to some other Linux machine, in order to restore the file system or the data.

What is very interesting is that the hard drive is recognized by the BIOS, and when I ran the BIOS tests on it, they appear to work fine, although they finish too quickly, it's like it recognizes the drive to be very small (it's a 160GB HD, and the tests - short and long - should take at least couple of minutes, and not seconds).

When I start the operating system, I see the drive is not recognized (there is no proper file under /dev ), and obviously there is nothing interesting in using 'hwinfo', 'fdisk -l', 'testdisk' .

Why is it that the BIOS recognizes the HD and the OS don't?
What can I do from here?

testdisk finds lost partitions. Did you really run testdisk on it with nothing except the 160Gb? Seems pretty fatal, then. Let's resort to dodges and wheezes

OS and BIOS are separate software. You try
fdisk /dev/whatsit
p <enter>
q <enter>

check the partitions and cylinders/heads/sectors info. You might also get inventive with dd. The idea is

dd if=/dev/whatsit of=/somewhere/else bs=iG count=1000

Now of course where you put it matters, but you might be able to rescue stuff that way. There is also the 'skip' instruction.

I would finally line up a credit card and ring the disk manufacturer. You might be able to do things about the card, but keep the actual hardware.

testdisk finds lost partitions. Did you really run testdisk on it with nothing except the 160Gb? Seems pretty fatal, then. Let's resort to dodges and wheezes

OS and BIOS are separate software. You try
fdisk /dev/whatsit
p <enter>
q <enter>

check the partitions and cylinders/heads/sectors info. You might also get inventive with dd. The idea is

dd if=/dev/whatsit of=/somewhere/else bs=iG count=1000

Now of course where you put it matters, but you might be able to rescue stuff that way. There is also the 'skip' instruction.

I would finally line up a credit card and ring the disk manufacturer. You might be able to do things about the card on the disk, but keep the actual hardware with the information on it.