Did you install new batteries in the remotes? If not, just pry open the remote at the key ring end, and install a new CR2032 battery that you can get at the grocery or drug store, snap it closed and you should be back in business. Then you can check the emergency horn function. If the emergency horn function works, then it's not the horn that has failed. The fault will be the clockspring in the steering wheel. If the emergency horn function does not work, the check the horn fuse at fuse position #4 (5amp fuse) in the front power distribution panel under the hood, and the relay #6 by switching out that relay with the one next to it and checking for emergency horn function. If the emergency horn function still doesn't work, chances are the has gone bad and needs to be replaced.
I've just recently had this problem so I'm speaking from experience here. Good luck.