Powersupply is that thing on the back of your PC with a power jack (i think thats what its called in english), its the thing you plug into your home electricity and it supplies power to all of your computer components. Open up the case and look at the power supply box to see if there is any noticeable damage (probably won't be though) make sure that all the wires running from the power supply are properly connected to everything, make sure that the wire running from your mobo to your power button is properly connected...if you have another computer I'd take that power supply out and test it with it, just take it out, put it in another case, connect all the wires and see if that computer will power up, if it doesn't power its defenetly a PSU problem (Power Supply Unit)....dumb question is your PSU off/on switch set to on?
The switch should be on PSU, I don't know how preassembled emachines ones are laid out though...hmm...thats weird...okay look at the wire that runs from the power supply to the motherboard is the connector in all the way? If it is then check the wire that runs from the motherboard to the power button is it in all the way? If all is in all the way then I think its a power supply problem, has this computer worked fine before? Maybe your electric outlet is ****ed up try turning it on in a different room, thats all I can think about without looking at it, send a picture or two my way of the insides of your computer.
