For some reoson my modded minecraft won't load. Why?

So i download on mod, the "cars and drives" mod because it kept breaking my game with messed up textures but after i completed the installation i click play on minecraft forge and as usual it comes up with the mojang sign but underneath there's an anvil being hit by a hammer with a loading bar and i don't know why but it always loads to 2 then stops, any reasons why or how to stop it?

Usually the main reason is that the mods are not updated to the current version of Minecraft. It's tough to keep up with mods because Minecraft updates so often.

That game is so 2010.

Chris thanks for helping butthe only mod that could make this happen would be cars and drives and i even tried removing the mod from the folder many times, i only know this as i started minecraft forge up then closed it and downloaded cars and drives after. Know any way to completely uninstall a mod?