Gennyo

So I've been playing crazycraft for a few days now but I don't know what I did. I load the modpack, open my single player world(Although when I create a new world, it works), and it's only open for a brief second. It then closes like I logged out; even minecraft itself closes. This happens everytime I open it and I really don't want to lose my world. If anyone could help me, i'd appreciate it.