It's entirely possible the drive was damaged when the power went out. So hopefully you have backups of anything important, otherwise you're looking at probably a couple grand to send it off to a recovery service. Might not be a bad idea to take it somewhere and get an opinion from someone who can actually look at the system though.
Help! The power went off several times recently and this is the only thing I can attribute this problem with. I turned my desktop emachines back on and it would not boot up. After trying everything possible, I decided to try to re-install Vista OS w/ the disc that came with the computer (didn't want to restore factory fresh due to loosing everything) but it wouldn't let me. Couldn't find any drivers and msg said "no hard drive found? What would cause this and is there anything I can do to gain access to my computer and files again?! I'm desperate, a lot of near and dear to my heart files on that computer... I spent over 3 long aspirating hours working on this issue. Can someone shed some light? Please?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic