i can't start my computer

[kkt]

i am having a problem with my computer.
i can't find anything on my screen when i switched on my computer but the cpu fans,dvd drive and processor is running.
there is no beep sound from the cpu.
i am using intel 945 model motherboard.
when this problem occured last time,i disconnected all external devices and restarted.it worked for few months but now i can't solve this problem even though i checked the ram by changing the ram slots but it is of no use.
so, someone kindly provide with me a super solution ??? 

[dahlarbear]

1.  No Beep.  Does your computer normally beep upon successful startup?  One Beep?

2.  No Display.
     a.  Nothing at all displays on the monitor during system startup?  Not even a "No video signal" message when computer is powered off, but display is powered on?

     b.  What is the "state" of the display's front power LED?  On/off,  solid/blinking, what color?  What "states" does it go through from power off to power on to system startup?

[kkt]

when my computer is woking properly the LED is in dark blue color.but now when  i switch on my computer it is in dark blue for 3 or 4 sec and goes to yellow color.
first,i thought that the problem is with my LCD screen but it is displaying check signal cable when the cord wire is disconnected from cpu.
 
ya, my computer will beep normally upon successful startup.

[kkt]

1.  No Beep.  Does your computer normally beep upon successful startup?  One Beep?

2.  No Display.
     a.  Nothing at all displays on the monitor during system startup?  Not even a "No video signal" message when computer is powered off, but display is powered on?

     b.  What is the "state" of the display's front power LED?  On/off,  solid/blinking, what color?  What "states" does it go through from power off to power on to system startup?

..

[kkt]

1.  No Beep.  Does your computer normally beep upon successful startup?  One Beep?

2.  No Display.
     a.  Nothing at all displays on the monitor during system startup?  Not even a "No video signal" message when computer is powered off, but display is powered on?

     b.  What is the "state" of the display's front power LED?  On/off,  solid/blinking, what color?  What "states" does it go through from power off to power on to system startup?

when my computer is woking properly the LED is in dark blue color.but now when  i switch on my computer it is in dark blue for 3 or 4 sec and goes to yellow color.
first,i thought that the problem is with my LCD screen but it is displaying check signal cable when the cord wire is disconnected from cpu.
 
ya, my computer will beep normally upon successful startup.