Long story short: I was installing a WLAN card in a free PCI slot. When I tried to boot after that, the (USB) keyboard was not responding, and the computer was entirely unable to boot, complaining about a boot disk read error (a BIOS error, I think). After removing the haunted WLAN card again, the USB keyboard worked again, but the drive still won't boot; albeit in a different fashion.

The BIOS seems to correctly identify my three hard drives (all identical Samsung SP2504C), both at startup and in system setup, but can't off of the one that has my operating system on it. When it gets that far, it just stops doing anything. It doesn't freeze per se... the cursor is still blinking, showing activity, but nothing further happens.

Running a recovery console reveals that Windows is unable to detect a pre-existing installation, and trying to cd to C: results in... well, I can go there, but there's nothing there. The console effectively behaves as if the C:, D: and E: drives were DVD drives or floppy drives with no disk inserted, throwing an error if I try any meaningful operation on either.

My googling has brought up people who have had this problem and fixed it by disabling RAID in their BIOS, but that's not it here. RAID is disabled, and always has been as far as I know.

Yes, I can--how do you think I managed to get into the recovery console? IRQs, what? Boot order is irrelevant.

It displays them briefly on boot, but I'm not sure what to look for. A few devices are sharing IRQ 11, I think, but I don't know if that's intentional or not. The WLAN card has been long excised, it's no longer in there at all.

I'm not sure what type of mother board it is, but in any case you definatly should update the BIOS once its up and running again. Then again you may have damaged a cable or something... Try swaping HD cables and make sure the drive is grounded to the case... The BIOS does make changes to irq's and stuff and the fact that the card is no longer there does not matter... If nothing else is working, then you could reset the CMOS and try again... You also may need to reset some other information in the bios.

I have already done the "Reset CMOS" thing, and it did not help. And how am I supposed to update the CMOS anyway? And why do you think it would help? Wouldn't it just potentially compound the issues I already have?

And none of this explains why the drives are behaving the way they are in the first place. Remember, the WLAN card is no longer in there.

You said that you had two devices sharing IRQ 11 right?

Here's something else from the book :

Don't know if that applies , don't know what devices were sharing the IRQ.

More from book :
CMOS can be updated by means of the motherboard manufacturers specific BIOS flasher and binary BIOS file itself. Following directions explicitly is a must as well as making absolutely sure it is the correct patch. Improper installation can result in a totally unuseable MOBO.

BIOS updates generally expand a motherboard's support for newer equipment , being able to use more memory , so on.

True , but your computer didn't bonk until you put it in though , did it. So it changed something funny around.

Have you checked to make sure all the cables are seated properly? You might have knocked something loose working in there.

Have any of the BIOS settings changed since you reset the CMOS?

At least try it, and if it doesn't work, well, then your fucked. BUT, you don't know if it wont work... Try it!

Vanneto Don't poke the bear. He's liable to maul you.
(-Edit- didn't post in time , I was about to warn you)

- X-G -
No , please don't try updating the BIOS yet.

You said you are booting from CD. What OS are you using? If you're using Windows , you can go to the Device Manager click on the View tab and select Resources By Type.
Now expand the IRQ listing on the left. See if that looks okay. (No doubling)

From your OP

It is possible that your boot order got screwed up. If the BIOS doesn't find the Boot Partition on your OS drive , it's possible its no longer being checked for as a boot device. Go into your CMOS setup / BIOS setup screen and look for boot order.

"Reset CMOS" is not the same as "Reset ESCD". That "Reset ESCD" option is somewhere inside one of the other BIOS configuration pages. readme

If that fails and you still can't boot, take the drives to another Windows machine and mount them there to see if at least all your data is still there. If it isn't, you won't get around reinstalling anyway.

You have to do things in order or you will get crazy.

First, check if your hard drive isn't dead. Use a Linux Live CD like Knoppix (600MB download) and see if you can browse through the filesystem.
I've had many HDD die on me by just swithching hardware in the box, probably due to pure randomness or the lack of anti static-wrist thingie.
And the WiFi card could have just damaged the drives.

Anyway, if that works and you can browse in WINDOWS correctly, try to reformat the MBR correctly.

If that does't do the job, then you know the HDD is fine and you can start to look in the BIOS issues.
What are your disks anyway, IDE or ATA-II ? I had to change my ATA controller mode in the BIOS to be able to detect my drive.

S-ATA drives. The IDE optical drives work, the S-ATA hard drives don't. I don't know if that's relevant. The drives aren't dead, unless three drives somehow mysteriously failed in exactly the same way at exactly the same moment. I can't get at them at all.

Dennis, the only option is "Reset to Optimized Defaults".

You said that the BIOS detect and list them, but cannot access data on them, right ?

Well good luck with wild guesses then... Your power supply could have failed and overpowered all HDDs thanks to a bad card. You will never know if you don't try.

Edit: To get my SATA to boot once I installed my current box, I had to change the SATA Mode (or something like that) from ENHANCED to REGULAR. Look for such a setting and try it

In my Award Bios, the option is hidden under "PnP/PCI Configurations" and on that page it is called "Reset Configuration Data" which can be set to enabled or disabled. This should be set to enabled to do the reset of the ESCD(Extended System Configuration Data), it will automatically set itself back to disabled after it has done the reset.