Sometime my PC moniters colours changes itself like from normal colour to green colour. How do I solve it?

Could be either the video card has gone bad or the monitor itself. Only way to troubleshoot is to swap each device one at a time.

I saw the email you sent me but we should answer question within the thread.

Is this a work computer or a home computer? If it's from work then you'd call your IT dept and thet would take care of it. If it is a home computer your options are either it's on warranty (new computer) or you'll need to buy a new monitor. Depending on your financial situation and your geographic location you may be able to get a used 17" CRT for a very low price at a used computer parts store.

As Need has said,the video card could have gone bad.Check the driver files (uninstall,then reload them) either from the card-cd disk,or from the manufacturers website.Make sure your display settings are not set incorrectly.If I push my monitor settings to maximum,I get a pink glow down the left side of my monitor.Not recommended.Now I have it set correctly.Also try downgrading from 32bit color,to 16 bit,to see what happens in Display.