samsung curved monitor went black with lines down the middle

First, unplug the cable from the PC and leave the monitor on by itself. If it shows the no signal message cleanly without the lines, the panel is fine and it's a cable or GPU issue. If the lines are there even on the monitor's own menu or the no signal screen, that's the panel or the board behind it, and that's a repair or replace job, not a settings fix. Try a different cable and a different input anyway before you give up. If it's under warranty, start that now.