What happened to my LG 42'' LW570Y?

sergei shtukmaister the very first thing you want to check on is your video inputs. Make sure you try all of them and see if that changes anything. If it does not, you will have to take the back cover off the TV and check the LVDS cables. Make sure that they are all properly seated and do not show any corrosion etc. If those check out okay then it gets to the board level. Check your main board for any damaged components and the same for the T-con board. Right now my prime suspect is a bad main board, then a bad T-con board and finally a bad LCD driver board (essentially your panel). Once you have the back cover removed take some good pictures off your boards and post those with your QUESTION. Adding images to an existing question - iFixit Repair Guide