Desktop stopped working

[nosignal1]

Okay, I have an emachines desktop which i got about 6 months ago. Today, when i went to turn it on, the green light came on like normal, then i turned the monitor on, but it said that there was no signal coming into the monitor.
When I turned the computer on, I heard the hard drive start up and the fan on the power supply is working.
I have no idea what's wrong. Can anyone help me?

 

[Harsh Pranami]

Check the cables that attach the monitor to the case.They should have got loose somehow.Do you hear any beeps?

 

[cboucher]

I had an emachine do the same thing. The onboard video went out. If you have a old video card lying around try installing it to verify.