I bought a computer and I was restoring it to a earlier date then I made a mistake and cut the power off now when I turn the computer on it won't start up

What exactly comes on screen if anything at all and what exactly happens?

What type of PC

vista or xp

Does your logo come up?

What comes up when you start your computer, press f8 while starting the PC and if works then select directory services, if it works then reply, I will tell the further steps.