I have some variety of Zephyranthes out in my greenhouse is a pot. The plant is bombproof, I'm convinced. I know it is a Rain Lily but I don't remember which one. If I took a photo of it, would you be able to tell me if we have the same plant?
If not, the Rain Lily I have has never laid flat to the ground as you describe. Is it possible an animal bedded down for the night and flattened them or possibly heavy rains? It would be very difficult to stake them.
One thing, if they are green they are photosynthesizing regardless of whether they are on the ground or not so they might come back up on their own.