Personal server Cache

Unfortunately it's not always possible to revert your world and go back to an older save. The cache folder only contains some of the world data, usually just information about the world generation, i.e. it contains no information about the buildings etc.
The only place which contains world data is the hidden ".backup" folder in your World directory. The worlds are only saved there when a new update arrives which changes the world generation (or anything which requires a world conversion). You could only use these worlds if they're not too old (otherwise it might not work), also keep in mind that these worlds do not contain any image data, so it would be necessary to copy the "customImages" folder of your current world. Basically the intention of the ".backup" folder is just to have a "fallback" in case a world conversion (for a new update) goes wrong (so your world isn't lost).