computer screen

From your description, it appears that the monitor has been damaged, and will probably require replacement. That's expensive. Once you obtain an estimate, you will be better positioned to know whether or not you should simply replace the laptop.

Rick/Portland, OR

A replacement LCD display, and the cost of the labor to install it, can easily top $400. Since new laptop can be had for around $650 or so, it does not always make sense.

Ebay is a good place to sell it, as-is, for parts. Alternately, if you're handy with electronics, look for a laptop like yours on ebay that has a bad motherboard (but a good display). I've 'frankensteined' several laptops and LCD displays this way.

What you are seeing on the screen is evidence of damage to the membranes that form the pixels, and the pixels are now dead - locked in the colour they are displaying.

Replacement as Nepenthe0 has said, may prove more expensive than the cost of a new laptop.

I'm afraid your screen is hosed.