I've got this problem with my tv too.
I got rid of it ages ago but can't remeber exactly how to do it. I think you definately need the remote as you need to hold down the button under the cover one in from the right with either text or the tv button for around 15 - 20 seconds(you have to press the bottom button first). Then turn off the tv and hold down tv button for 10 secs, turn on (not sure if you have to hold down tv button again).
sam, December 2007