Turn signals stopped working but were working yesterday. Any ideas?

More than likely the electronic turn signal flasher is defective.
Instructions

1. Remove the Old Flasher Relay
   • Using your socket wrench, disconnect the negative cable from the car's battery terminal. The negative terminal and cable are identified on the top of the battery using the minus ("--") symbol. Once the cable is disconnected, wrap the metal end completely with the black electrical tape. Lay the cable down and make sure it's not touching any metal surfaces.
     
   • 2Open the driver side front door and kneel or position yourself so that you're able to see under the dashboard.
     

   
   

   • 3Locate the automotive flasher relay under the dashboard on the right-hand side. The flasher relay is about the same size as an ice cube. It will be held in place by one screw and will have a three-pronged wiring harness connected to it.
     
   • 4Remove the screw holding the flasher relay in place and slowly lower it from underneath the dashboard.
     
   • 5Hold the flasher relay in one hand, and with the other hand gently disconnect the wiring harness plug from the relay. Never separate the flasher relay by pulling the harness off by the wires, always hold the plastic harness plug itself.
     
   Install the New Flasher Relay
   • 6Inspect the new flasher relay to make sure it isn't damaged. Hold the new flasher relay and the old one side by side and compare them, ensuring that they are exactly the same.
     
   • 7Carefully plug the wiring harness connector into the new flasher relay. Make sure no other wires are intertwined as you raise the flasher and harness back into position under the dashboard.
     
   • 8Secure the flasher relay by returning its mounting screw.
     
   • 9Unwrap the negative battery cable's connector and reattach it to the car's battery terminal. Turn the power on or start your car and test out the new flasher relay to make sure it's working properly