SAHITYASHRIVASTAVA ,

Try running the LCD BIST(Built in self test). To run the LCD BIST (Built in Self-test) Press and hold the D key on the keyboard while pressing the power button, then release both at the same time.This will initiate A grey screen, then Red, then Blue, then Green then White.

If the issue persists when those color screens are displayed,than it may be an issue with the system LCD screen.

Further try connecting an external monitor and confirm if the display is fine.

If neither the self-test nor an external monitor works, your GPU has failed -- we'll need to know what model system you have to recommend replacement parts.

I tried buf it doesnt works