Can you de-build a unity progect to recover files?

Oh dear. I accidental deleted some core files containing impotent assets. (Terrain textures, trees, etc.) so now a project I have been working on is mostly blank and destroyed, BUT, I have a built version of the game on gamejolt. Is there a way to download the built game and de-build it? (Meaning reverting it to a project file? Here is the gamejolt page: https://gamejolt.com/games/ChillIslandGame/237169

Thanks!