2001 Buick Regal horn problem

My daughter had her turn signal switch replaced about a year ago on her 2001 Buick Regal LS. Ever since then, the horn won't blow. Could there be something as simple as a wire was left loose after the previous repair? All of the lights and buttons on the steering wheel work properly. Does the steering wheel have to be pulled to check for a possible loose wire? Thanks.

Welcome to AF.

Even though replacing the multifunction switch should not affect it possibly an issue with the clock spring at the steering column which helps transfer signals like the horn ground, stereo controls, airbag, etc since the steering wheel rotates. I'd have to double check but the horn ground may pass through the MFS switch assembly and its wiring harness so thats still a possibility.