Still in warranty?
Local TV repair shop?
Not really a lot of to go on here. If you are familiar with electronics repair you could disassemble it and see if there are any obvious defects on the circuit boards. Many places like ebay have people selling repair kits that include new capacitors (the usual suspect). Main board and power supply failure are quite common on TVs, but if the LCD has failed in anyway, then a new TV is what you need.
Other options would be to find the same model with a damaged screen, take its guts out and put them in yours to see if the LCD still works.
What it comes down to is time and money. Most TVs aren't worth the cost of repairs unless the failure is simple. You will pay some decently high minimum repair rates if you take it to a professional. Considering you can get low end 55" TVs for around $300, probably not worth taking it in for repair.
(They are also massive, so it would have to be local, not really something easily shipped even with the original box.)