FarFromSane

So I added some mods to my modpack and it now seems that my singleplayer worlds won't open! When I go to open them it loads for half a second and then spits me back to the main menu. I would think I install the mods wrong but I can join and play with no issues on my own modded server. This puzzled me and I can't find anything wrong in my own save file that I forgot to copy.... Edit: I can't even create a new world