What model number do you have, and from what country (as this can vary on responses)?
One of the digital channels (9.1) that has been functioning since I purchased the TV 2 years ago just disappeared. It continues to function on another SONY TV, so it is not an antenna issue. With the SONY TV you can actually manually program any analogue or digital channel, as it has a point ( . ) key. The SAMSUNG has no such point key so manually inputting a digital channel seems not to be possible. So, there are two issues, why did the signal disappear in the first place, and is there any way to manually input a digital channel on the SAMSUNG.