An LCD screen cannot produce enough light by itself. It needs an additional source of light.
A Backlight is used as the additional light source.
A Backlight is a CCFL.
Cold Cathode Fluorescent Lamp.
Similar to the Fluorescent lighting used in homes and businesses, but on a MUCH smaller scale.
The LCD screen is a composite of layers, surrounded by a thin metal frame that resembles a picture frame.
To one side of the LCD screen layers, and under the frame is usually where the Backlight is mounted.
[Note* Two Backlights are used in some models]
Replacing a Backlight is more labor intensive than replacing an Inverter.
Due to this, and the cost, the LCD screen itself is replaced as a unit most of the time, when it comes to Backlight replacement.
Example of a replacement LCD screen for the HP G5000 series of Notebook PC's,https://www.screentekinc.com/HP_G5000_Series--15.4-inch--1280x800-wxga-laptop-lcd-screen.shtml
[Note* Stating HP G5000 is just stating the model series. When buying replacement parts the EXACT Model Number should be used. This information is located on the bottom of the laptop, in a white Service Tag.
When replacing an LCD screen, the model number of the replacement LCD screen should be matched to the existing LCD screen's Model Number.
Inverters and LCD screens are matched together. Make sure you get the correct part]
An Inverter is used to provide power from the laptop to the LCD screen, and to the Backlight.
Note* 90 Percent of the time the problem is a bad Inverter.
Example of an Inverter for an HP G5000 series notebook PC,http://www.zlectronic.com/product/INVERTER-FOR-HP-DAC-07B035-DAC-09B017-DV5000-G5000.html
The LCD screen, Top Cover, Display Bezel, Inverter, Backlight, and various screws, make up the Display Assembly.
The Display Bezel made of plastic surrounding the LCD screen, and in front of the LCD screen is removable.
Behind it is easy access to the Inverter.
The Inverter is approximately 4 inches long, and the width of a No.1 pencil.
Usually located at the bottom of the LCD screen, and right behind the Bezel.
This article shows replacing an Inverter and LCD screen on a Compaq Presario v2000 series Notebook PC,http://www.insidemylaptop.com/replace-lcd-screen-inverter-compaq-presario-v2000-laptop/
This pictorial guide is not for the HP G5000 series Notebook PC, but the models are very similar when it comes to Inverter replacement.
The above link is to show you what is involved.
Please post questions in a Comment.