I completlly agree with jhtalisman, you probably killed the bios on your drive. Never, ever shut down the computer during a bios flash (for drives or motherboards or anything). Some drives can be recovered from a bad bios flash, others cannot. Check the lg forum to see if yours can. IF it hangs, leave it and hope to god it unhangs (never reboot).
I went to get you links to the lg forum and the faq (many dont read the faq stickies, but the drive specific faq's here rock so I always link to those too). So I just looked (bios flashing is easy to find in the faq, like I said, they rock, so I just looked). Aparentlly lg drives have a safe mode that trys to prevent a bad flash. Your drive may not be detected buy windows but may have been protected from a bad flash. If it wasn't, you are screwed, you cannot reflash an lg with a dead bios.
and then here
best of luck, firmware flashes are so safe, it kills me to see someone loose a drive to one (almost always caused by power falure, system hang, or other extreme circumstances). Fyi, if your system hung while doing it, I might look and see if there was a cause for the system hang (like the power supply or a defective component).