HDD Problem (rip?)

First of all, let me explain with details:


motherboard: Gigabyte EP45-DS3L (irrelevant, I think)
PSU: Cooler Master Extreme Power 650W
HDD1 (system): Seagate Barracuda 7200.11 500GB (the one with the problem)
HDD2: WD, 1TB. Can't remember the model. It's irrelevant because this one works, the other doesn't.
OS: Windows 7 Enterprise x64

All this info is just so you know.

Tonight the electricity was cut off. When it went back on, I turned on the computer and I got this message: DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER.

Just want to clarify that I've already tried following every procedure with no luck.

At first, the BIOS wouldn't recognize my 2 hard drives and wouldn't boot from the DVD, so I switched off and unplugged everything for a little while. After plugging back in, the BIOS read the HDD2 (WD), allowing me to boot from a DVD. But still no luck with the HDD1 (Seagate, OS in it).

I tried CMOS, swapped wires and ports on the motherboard, dancing around my house naked singing Sexy Bitch, nothing worked.

(AHCI disabled)

So the HDD started spinning, it wasn't completely dead. I put it on my brother's computer.

1) I replaced his HDD with my Seagate. The BIOS didn't recognize it, so I changed the port on the motherboard to make sure and nothing happened.
2) I connected both hard drives (mine and my brother's). Then, Windows would get stuck on the welcome screen, before showing the desk.

I've been told to leave it alone until tomorrow and try again, but meanwhile, I come here to look for more suggestions.

If there's anything else I can try to make it work again, excellent. If not, I'd like to know if there's any chance to recover the data in that HDD (more than 200GB in music, for example. All tagged including dates, front and back covers and even labels).

Thank you for reading.