How do you find your original spawn point if you changed your world spawn point in Minecraft

Elaboration:
I made a flat world set to creative and built on it for a few weeks. I wanted to change my spawn point to I used the command setworldspawn to move it over a little, fell out of the world, and when I respawned there was nothing around me at all. I've flown all around the area and I've yet to see anything. The coordinates I respawned at were the ones I'd set when i set the world spawn, and there was nothing at (0,0,0) either. Are all my buildings lost or am I, and is there any way at all to get back? I unfortunately don't have any backup saves because I'm dumb.