My external HDD (3.5) drive had some bad sectors so I decided to Low Level Format it (first time doing it) using the Low Level Format Tool by HDD Guru. After I left it all night long, I found out it encountered an error while at 96% complete. I stopped the process, yet the system didn't recognize the drive in any form any more (Windows 7). Meanwhile, after some unsuccessful trials, the Low Level Format Tool still recognized the device. I decided to perform a Quick Format, hoping that it will bypass the bad sectors and just make it work again, however, it got stuck at 92% and now, not even the Tool recognizes it.

Things I have tried:
Control Panel - Administrative Tools - Doesn't see the device (both after Low Level Format and after Quick Format)
Windows XP Setup Boot - Doesn't see the device (both after LLF and after QF)
Partition Manager - Doesn't see the device (both after LLF and after QF)

I don't remember the error, but I believe it is the "Timer - unknown error".

HDD: Seagate Barracuda 7200.10, 500 gb, ST3500830A, Firmware 3.AAD.

Thank you in advance for any reply!