Backlight is an option on that model and you can change it out if you are adept at working on notebooks. I do a lot of laptop rebuilds and usually EBay is the go to place for Dell parts (the best deals are often out of China). For your model, HERE
is a compatible backlit KB, insure that you also get the optional backlit ribbon needed for that model as you will see in the manual referenced below.
The first thing to do though is download the Dell Service Manual
to decide if you can do it yourself. And if you do, careful with the ribbon cables.