Bought two LCD to replace and still no Video.

it's a bit hard to understand what you're saying, but it sounds like you're trying to replace the screen on your MacBook Air, and aren't able to see anything on the screen.

My best guess is that the backlight isn't turning on for some reason. I can see two possible causes for this: 1) it isn't plugged in, or 2) it's broken.

I'd check for (1) first, and if that doesn't work, it's probable that you have a faulty backlight. I've found that I can see my laptop screen in bright, direct sunlight, even with the backlight off, so you might try shining a really bright light at it when the laptop is on, to see if the screen is working, even if the backlight isn't.

If you have removed the back from the LCD, you could also try shining a light at the back of the LCD to see if you can see anything.