Keyboard light not working

Are you certain that it has a backlit keyboard? Backlit keyboard was optional on that laptop. Perhaps the original purchaser did not order the optional backlit keyboard. If it's important, you can buy a backlit keyboard here and install it, or pay someone to install it.

If it has backlighting, it can be enabled/disabled via a Fn key with Fn modifier, and possibly in Mobility Center and possibly in BIOS.

What's  an FN modifier, ive tried updating my bios, still nothing, it actually came with a backlight, but the person i got it from said it had, that a possible update might have messed up with it

Fn modifier key is the key at lower left of the keyboard labelled "Fn". When you hold that key and press a function key, instead of the default function key behaviour you will get some additional behaviour included with your laptop. For example, on my Dell laptop pressing F6 key plus the Fn key will toggle the keyboard backlight on/off.

Look on your function keys (F1 through F12). Do you see one with a sort of lightbulb icon or something that could represent light? Try it with the Fn key. Try all the function keys with Fn. If you don't have a function key with an icon for keyboard backlight, then you don't have a backlit keyboard. 

If you do have a function key with a keyboard backlighting icon and it doesn't work when you press it with Fn key, then you may have a hardware issue. You could open the laptop to see if the keyboard backlighting cable is connected. It would be a relatively narrow cable from the keyboard, narrower than the main keyboard data cable.

Did the seller ever see the backlit keyboard work on that laptop? Did you see it work?

Are the lights on every board lit?