My samsung 910 Monitor has horizonal lines going through the picture***
If the lines are stationary then the damage may be in the screen itself
IF in just a part of the screen that may not be fixable.
If covering the entire screen, then check to see if the screen has a
ribbon on the rear connecting the top board to the side board.
Check the ribbon that goes from the video board to the back of the screen, see if moving it about changes anything.
If the lines move up and down, then the problem may be in the video
card itself. This usually isn't fixable or should I say not worth the
cost to fix if you can find someone that does video chips.