No display but PC turns on

[Orbit_]

So when I plug in my PC, the green light turns on in the back. When I press the power button it doesn't light up anymore, but I get fans and my disk drive on. When I plug in my VGA it doesn't show anything on the monitor

 

[alexoiu]

What components? Is a case speaker connected to the board?

 

[Orbit_]

No, the only way I would hear sound is through USB speaker or aux cord/ headphones, why?

 

[Orbit_]

And I've tested the USB ports, and none of them work, maybe all ports on my PC are broken?
I plugged in the PC earlier today and it worked, then I put the case back on and from then on out it doesn't work anymore

 

[Paul NZ]

Is it VGA on the monitor and on the case?

 

[Orbit_]

It is dvi on the case and VGA on the monitor, but I am using a dvi to VGA adapter, because I have no dvi cable

 

[Paul NZ]

You need an active adapter for DVI to VGA. Since DVI is digital and VGA is analog.

The 2 arent compatible with each other. Thats the reason why there's no signal

 

[Orbit_]

So I left the PC running with the cables plugged into the monitor as I went to my basement to grab a laptop to test the monitors VGA port, and when I came back to my room, the windows starting screen was on, and my computer is working now

 

[Orbit_]

But it sometimes doesn't work now, what's wrong with my PC?