I am very afraid I have no good news for you.
What you have is a LCD panel that has failed, this is a very common problem with these new LCD televisions and there is no way to fix it. The part price is always more than a new television. For example the part needed to fix your set is over $1000, you can buy a new set for half that price. Unfortunately there are a lot of good folks in your position, they have bought these nice sets, and after 18 months to 4 years the tv is going into the garbage unless they bought an extended warranty on it.
The only bit of advice I can give you if you don't have a warranty is to call Sony and complain to them, a lot of manufactures are working with their customers because these sets are failing so prematurely. A lot of times the manufacture will repair the set, or supply the part at no cost, leaving you with the labor for installation.
I am sorry I have no good news for you, please let me know if there is anything else I can do for you.
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