Well, first thing I'd do is make sure everything is connected properly, this includes making sure the power strip is on. I know it sounds crazy, but people often turn them off, but forget to turn them back on.
Secondly, be certain you have given the mobo power. There should be two power cables connecting to the mobo, one of which should be the big power cable, then a smaller one that connects somewhere near the processor.
You need to make sure you've connected the power button from the tower to the correct location on the mobo. People often connect this improperly, or to the wrong place, and the computer never knows to power on.
Also, including a bit more information about your system is a big plus when trying to fix problems. Sometimes someone had a similar problem with a similar system, and can answer the question directly.
I tried to do that but nothing happened. Is the Power-sw switch same as power-on switch? because my manual says something about power-on.
I took out the main power connector to the motherboard and when I tried to put it back, i saw the case fan move and saw a red light and some sort of noise. the same thing happened before
Hmm, sounds like it could be shorting out somewhere. make sure that the mobo isn't touching anything metal, and that nothing metal is hanging around either on top of or behind the mobo. sometimes the mobo touches the case and can ground out. Power issues can be difficult to diagnose sometimes.
As a precaution, check your motherboard and look at the capacitors. They're the little cylinders, usually they're grouped together. Make sure they all look very uniform, and that none of them are buldged, swollen, burned, or leaking. We'll track down the problem. Hopefully someone else will join ina nd off their suggestions as well.
Also, be very carefull when dealing with power issues. Dangerous current goes through those electronics, take care not to hurt yourself. and NEVER work on components or hardware with teh unit plugged in. Just a warning, some people are silly.
::EDIT:: About the light coming on for a second when you reconnect the power, it sounds alot more like the board is grounding out somewhere. Only reason I can think of right now that would cause current to flow enough to spin a fan or light a light for a second.
Did you take the front of your case off? One time i took the front of the case off to put a fan in and ripped the wire off the power button. My friend's brother soldered it back together and everything worked fine.