HI to all, My LG CRT monitor was running in 600 x 800 resolution, and when I tried to increase it The screen went blank and never returned till now..only sparking sound coming from inside the monitor...Please help.
You no doubt exceeded the resolution it was capable of.
If you're getting a sparking sound you probably destroyed it. Most modern monitors won't suffer damage from this but the older ones certainly could.
When you add more lines to the screen you increase the pulse rate on the flyback transformer and the voltage goes up. It's already very, very high.