Screen problem light is very dim

@manjeetkum35357 either a bad backlight in your LCD screen or a bad connection on your display connector, bad LED driver or short circuit. I'd start by replacing the display. While you do so, you can check the display connector and see if there are any missing, burned or corroded pins on it. If you would give us the motherboard number, we could most likely also tell you the needed voltages for your backlight to check further. But since you only gave us limited information, the only advice to give you right now is to replace the screen.

Download the manual for your computer from here Luckily Dell places all the service information in their owners manual. Page 37 tells you how to replace the LCD.

While you work on your computer, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.