Try the following.
Hello,
You mentioned the BIOS. The first thing to check is that the system still recognises that you actually have a harddisk. Go into the BIOS to do this.
AMI BIOS key press is 'del'. A lot of the other BIOs's now use this, but if that key press does not work try 'F10' for Compaq, 'F2' or 'Shift+F2', 'Shift+Esc'.
If the BIOS does not see the harddisk try auto-detecting it. Most BIOS's have this option.
If the system does not see the Harddisk you will need to check the connections on the IDE cable. Listen to the harddisk when you turn on the computer. It should initialise and make a noise. Listen to a working one to recognise the noise pattern.
Do NOT do a low-level format on an IDE hardisk, it is very likely that it will not work correctly and the disk will be ruined forever.
If fdisk does not see any fixed disks when you run it, then it is not working. You could try it another computer, but that would mean setting the jumper(s) on the drive correctly. Do you know what make and model of harddisk it is?
If you have gone through everything and you still have no luck then get hold of a set of boot installation disks for NT4 or W2k. There are 4 in the set. It does not matter that you don't have or are not installing either of these operating systems. When you boot with these & go through the start of the installation you will get the chance to view, delete & create partitions.
If you want a set of these disks, I can e-Mail you a zipped file with the disk images and the program(s) to make them. The zipped file is 3.39MB
Good luck :grinthumb