Most likely, you made the number one mistake of TV and video equipment owners: failure to use a surge protector. People will spend thousands on an HDTV, then fail to spend a tiny fraction of that to protect it from the necessity of a very expensive repair bill. Voltage surges on the power line are a *very* common cause for electronic equipment failures, especially HDTVs.
Your TV's power supply has been taken out by a voltage surge on the power line, common during storms or other power outages. It might be repairable, but you'll have to take it to a service shop to find out.
While it's in the shop, visit the electrical department of a large hardware store and buy yourself two surge protectors. Don’t get the cheapest you can find. Those selling in the U.S. for around $10 to $15 USD are little more than power strips. You should expect to pay in the range of $30 to $50 USD or more for a unit that will confidently protect a few thousand dollars worth equipment.
Check the specs on any surge protector you’re considering. Look for the Underwriters Laboratories (UL) label, a transient or clamping voltage of 330 volts (both for U.S. systems), and a joule rating in the thousands (2000 to 4000 or more).
Be sure to plug all of your electronics into the surge protector: TV, DVD player, cable or satellite box, home theater receiver, surround sound amplifier. etc. The second one is for your computer and its peripherals (printer, scanner, Internet modem, router, etc.). If it’s electronic, it’s at risk for surge damage.
Surge protectors come with a monitoring circuit that continually tests its quality. When it’s providing full protection, an LED or other light is illuminated and remains steady. If the light goes out or begins to blink, the surge protector should be replaced. (It can still be used as a power strip but not a surge protector.)