I have a Dell Latitude that I replaced a backlight and inverter on, but now there are two vertical lines on the left hand side of the screen, purple and green. What is the source of these lines and what do I need to do to get rid of them?

How wide are the lines? If they are just a pixel or so wide then a colum or two of pixels may be dead, and you'd need to replace the screen to resolve that issue as far as I know.

The two lines are very narrow and are about 3/8" apart.

Sounds like dead pixel colums.

I agree they are likely dead pixel columns.