what makes turn signals stop blinking?

There is a plastic thing in side the stering colum. When you turn the signal on then turn the wheel it catches some thing in side there. Then when you turn the wheel back it tuches some thing else and springs back turning your signal off automaticly. There is a catch on each side, one for the left signal and one for the right. It sounds like the one that does the left side is broke off. It is just plastic. You need to take your wheel off and get in side wour stering colum to fix it.