Click the blue DELL-Cares username. Their profile page will appear. On the right click, "Send this user a private message". They will need the private PC Service Tag. Or you can click the red, "Get help now" icon on the right to start a live chat session.

What BIOS is currently installed?
What software or driver changes did you make just prior to the issue appearing?

Post a picture of your BIOS-Advanced screen. This is what we see in the documentation =

From beginning when it is purchased In BIOS touchpad backlight option not appearing.

Unfortunately your model does not have the option of the backlit touchpad. I believe that only the units specced with the RTX 3080 had the backlit option. 

Also, please remove your Service Tag from your post, for security reasons. 

You believe  or dead sure. Because, believe means shows some hope.

I because while purchasing was not aware of this. Otherwise, definitely i would have gone for this GTX 3080 only. So, please let me know i can have some hope. Is it BIOS or software dependent or is a hardware specific.

yeah 3080 only. Probably to entice people to spend the extra for the 3080.