Why isnt crysis 2 installing on my computer?

I recently bought crysis 2 and have been playing it for a few days, anyway i uninstalled it as a number of graphical glitchs were messing up some missions preety bad so I uninstalled and re installed and when it asks for the rego code i type it in its says its valid then nothing happens, whats going on.Why isnt crysis 2 installing on my computer?
Registration codes are only meant to be used once, I'm not sure how to overcome this but try again until something happens, which I doubt. Perhaps you can return the game and ask for a new one and come up with a liable excuse.