Thanx for all the help guys.. i think it was the problem with the fps.. i read sumwhere that, if a device loses (depletes) it's battery then it's fps may get wrong, so the technique was to keep it idle for some time.. but how i fixed it was by keeping the charger in, removing the battery and again re- inserting it, voila- the screen is working alright, this trick may help some... it took me 4-5 tries like this to get it working, so don't get disappointed if it doesn't work after a try!!!
Hit thanks if you liked my post!!
it is easier to hit than typing
Micromax P300 thread- http://forum.xda-developers.com/show....php?t=2313795