Question details:

After taking my system to another city through truck, monitor is displaying many colours simultaneously.

Answer

Probably it is a hardware problem. Check that all cables fits perfectly in their holes and the video card is seated in it's slot.

If all fits perfectly it could be the fact that your monitor, video card or video cable was damaged during transport.

Test your computer with another monitor to see if the monitor or your video card is the problem. Do the same with your monitor and other video card. After identifying the damaged component take it to a computer repair store.