Like hang-the-9 said it will most likely cost less to get a new one. Unless it is a very expensive TV. I took a 47" Samsung 3D Smart TV that would not turn on and spent $100 for a new control board. Works like new now.
What exactly is wrong with it? If the screen is the problem and needs to be replaced then you are SOL and need to just get a new TV since new screens cost about as much as a new TV.