Do you know what system version it was running?
OK then I'm afraid there is a hardware failure that I can't determine here. If you had the install disk there is more we could try. Could be the hard drive or something more complicated you will need to take it in to a technician to look at it, sorry...
OK good luck
Hello there! If you have another computer we could create a rescue disk for your mac. I can assue you as long as your mac boots and you see the apple icon your hardware is working.