Looks like one of the actual layers of the LCD sandwich has shifted slightly in the drop - noting when you take apart an LCD watch if you don't line up the polarising film, you will get an all black or inverted display.
Since you've little to lose, it could be repaired by stripping down the LCD panel, but obviously dismantling this can cause other issues, and dust.
http://electronics.howstuffworks.com/lcd2.htm
The poor man's fix would be to run the Gamma utility (I think Adobe created it, it is a small control panel), and invert the colours system-wide
It might actually do the trick!
JB
Since you've little to lose, it could be repaired by stripping down the LCD panel, but obviously dismantling this can cause other issues, and dust.
http://electronics.howstuffworks.com/lcd2.htm
The poor man's fix would be to run the Gamma utility (I think Adobe created it, it is a small control panel), and invert the colours system-wide
It might actually do the trick!JB