sinnoc: how on earth does that help right now?
computerdim: the lightbulb is usually just power, and the cylindar icon is for the hard drive (the hard drive is like a load of stacked up cylindars, made from magnetic tape like in a VHS).
if the monitor says "no video imput" then it sounds to me as though the monitor is fine, and it isn't getting a signal from the graphics card inside the computer. so, check your wiring as said above (make sure the cables haven't come a bit loose or anything). if it doesn't help, then you may have a dud graphics card.
as much as i hate to recommend them, one idea is to go to a local PC world and have their help desk check it over. if the computer is still under warranty, see if anything can be done that way first.