Screen brightness adjust key

From this web site:
http://www.computerhope.com/issues/ch000594.htm
How do I adjust my brightness or contrast on my laptop? Every laptop is different, so adjusting the brightness or contrast on your laptop may vary from the steps provided on this page. However, understanding the process of how to adjust the brightness or contrast will help you change your settings.
Most laptops adjust their brightness and other settings using the function key in conjunction with another key. For example, pressing and holding the function key (abbreviated as "Fn") and pressing the up or down arrow keys as shown in the picture below, increases and decreases the brightness.

Other examples also shown in the above picture include pressing Fn and F1 and F2 or F7 and F8 to increase and decrease the brightness. If none of the above examples resemble your keyboard look for keys on the keyboard that have pictures of a sun or a half moon to identify the correct key to adjust the brightness.
How can I adjust the laptop contrast? Laptops only allow users to adjust the brightness of their screen. Contrast settings are not adjustable on a laptop display.
How do I save the new adjusted settings? After adjusting your laptops brightness it will retain the new settings.
Laptop brightness is still not enough or screen is black If after following the above steps your brightness is still not enough, plug your laptop into the wall to make sure it is not a power setting that is decreasing the brightness. If the laptop is plugged in but still is not bright enough, try the suggestions on the below link.

• My laptop computer screen is black.

1. Hold down the Fn key located at bottom left of your keyboard next to the Ctrl key.
2. Adjust the screen brightness using the up and down arrow keys located near the bottom right corner of the keyboard.

screen back light on the other side is busted which need replacement.

I have looked at all of the available pictures of this model PC and all of the images show a Fn key on the lower left side of the keyboard. It is one key to the right of the Ctrl key (the bottom right key on the keyboard)

Let me know if you need anything else.

Press on the "Fn," or function, key. It is located in the bottom-left corner of the keyboard, typically next to the "Ctrl," or control, key. Do not depress it.

2

Press on the "F8" key, which is located in the middle of the Presario's top-most row of keys. You should now be holding down the two keys simultaneously. Small illustrations of a sun and half moon often accompany the F keys allowing you to adjust screen brightness.

3

Monitor the progress bar that appears on your screen as the brightness increases.

4

Release the two keys once you have achieved the desired brightness.

If when you say faint you mean you can barely make out an image then the problem is most likely the backlight inverter in the screen assembly has gone bad. If what you mean is that the brightness got turned all the way down then it's just a matter of adjusting the brightness of the screen by holding down the function key (Fn) and pressing the LCD screen brightness adjustment keys noted usually by a picture of a sun or something similar accompanied by an up or down arrow.

if the display is faint, try to increase the brightness using ur Functional key (Fn) & ur Functional Key (F4, F5, or F6)

yes

It may have something to do with your adjustment of the LCD's brightness. Look for the brightness key in your keyboard and adjust it. Usually it goes with the Fn button.