Well if the picture appears totally green then it indicates that both the red and blue drives have failed, unfortunately there isn't anything of a non technical nature that can be done by a owner to cure the problem, this said of course assuming that the set is used on its own and not driven by an external set top box etc, as if it is check that all rear connection plugs are firmly connected. You should also have mentioned what model you are referring to, as some may well be known to suffer from stock faults such as described.