If caused by malware, it is often possible to start the machine in Safe mode and run anti-virus/spy-ware utilities, and HijackThis to locate and remove/correct the problem. It can also be helpful to try a different monitor as well as learn how to work in the dark i.e. learn the keyboard commands for running the anti virus and anti spyware utilities as well as System Restore.
For keyboard shortcuts regarding particular programs contact their Support team or forums. Or see http://www.geocities.com/~budallen/hotkeys.html#Make%20Your%20own
Also, a completely dead monitor is often indicative of loose or unplugged cables.
System: emachine, P4, 3.06Ghz, 512mb, xp-home edition and ATI Radeon xpress. Now i installed a new HP printer and AVG free editon. System runs fine for two days.Third day upon turning on the computer, the PC turns on but my monitor remains black.For 3 days the problem persist. Without visual i know not what to fix. Took the PC to the shop and within six hours i was told that my PC is ready. I was told that malware spyware was the cause. What could i have done to solve this problem myself. How can i bring up the screen to see what to do next time around