There is a YouTube video addressing this exact problem.
You can watch it, but here's with a try.
Follow these steps.
Turn on the TV.
Press the home page button 5 times.
Press the curser up button 1 time
Press the rewind button 2 times.
Press the fast forward button 2 times.
The TV should start a reset and will likely turn on and off two or three times. Takes up to ten minutes.
Seems to be a common problem.
And I would watch the short video on YouTube first if you're not real tech savvy.
Hope this helps. Good luck.