(1) tell us it's win7 or some other windows as Kikireeki asks.
(2) remove all USB connected devices (printers, usb disk, mp3 players, tablets, flash drives, external disks, etc.) -- seriously this helps.
(3) remove any network cables
(4) Boot and tell windows to start in safe mode. And then tell us what happens, what messages you see, whats the last thing that happens, etc.
either your hardware was hurt by the power fail, or this is a software problem unrelated to the hardware problem. The PCs actions like messages will help people figure out what is broken.