when turning on, get only a question mark on screen

Hi everyone, thanks for looking! My MacBook pro, upon turning on, only goes as far as showing a big fat question mark in the middle of the screen. It doesn't seem to be starting the operating system and I think that the hard drive is not working either. Is the Hard drive dead or is it a motherboard issue? How can I tell? This happened suddenly, after I repeatedly tapped on the touch pad in quick succession 10-15 times. If it is a hard drive issue, is there a way to "resuscitate" it? I have a lot of data on it.