Try turning the main power switch on the back of the tv off.
Then hold the menu button and push that switch back on while still holding the menu button.
Keep holding the menu button until the setup menu pops up.
Next, be sure your input is set correctly(air or cable).
Next, do an auto channel search.

That did it for me. After I shut it off I had to do it one more time but it did the job. A friend of mine gave me the tv for free because nobody he new could figure it out. I took it home, got lucky, and figured it out in about ten minutes.

Hope this works for you.