Sounds a bit dire.
When you restart it, do you see a Bios screen come up? Depending on quite a lot of factors, this bios screen could look like anything, but it will generally be the Motherboard manufacturer with some form of detail on how to get into the bios. This will then be followed by a whole bunch of text, which you have mentioned doesn't appear.
I would pull the power out of the back completely, leave it for two minutes, put it back in and restart it. Let us know exactly what you see on screen (if anything) so we know what point it hangs.
If you see absolutely nothing until a blinking cursor appears, you have a bigger problem than you are going to find help on here for, and that computer is going to have to be given to someone who knows what they are doing, because that will point towards hardware issues.
as Zesty said, yes this sounds like a motherboard failure. However, that can also be caused by a power supply playing up.
Most other faults you would still see a bios start screen, short of a video card failure.
Edited by Eirinn, 06 February 2011 - 03:15 PM.