Lost ITV channels and C4

I have suddenly lost all ITV Channels, Channel 4, E4 on my Samsung LCD TV with built in digital freeview. If i plug in a freeview box i can view the channels so it is not the aerial or reception.????????? ive lost all itv channels and channel 4 from my samsung lcd I have exactly the same problem on my new LG 32", lost all ITV & ch4 plus related channels. Put v old fashioned chunky TV back & plugged in digibox again and they were there. Am now thinking may just have to do without new tv or get sky, am thinking of trying another make also. Any solutions?