The app closed and when I opened it, my file was gone

Reset doesn't work either, it gives me just a black background with clocks and says "preset loaded"

Plwase help, I've had my live background for a long time now and I would hate to lose it

You can tap in the clock icon in the top right in the editor(near the disquette icon) here you have restore points(if you have made one in the past, or load points) try to tap in one of this points( the olds are best) and tap in the disquette to load the preset. Remember that you have the option to export a preset(if you have the paid version of Klwp) in the menu(the 3 lines in the top left of the editor) Export preset>put the name that you want>Export.This create a preset that you can use when you need it.