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Is there any sign of life from it at the moment, e.g. standby LED lit, sound (but no picture), etc.? If the LED comes on, is it blinking in a particular pattern?
To me, it seems like either its power supply went or the its processing unit has crashed (like a PC).
To start with, try unplugging the TV for a few minutes. If it still does not come on, try holding down the standby button (on the TV itself) while plugging it in. Repeat for each button on the TV in sequence. Some electronic equipment (especially set-top boxes) will perform a reset to factory defaults when a certain button is held down while powering on.