2003 Mitsubishi Lancer Problem with car horn

Hi I have a 2003 Mitsubishi Lancer and I've been having problems with the car horn. The button for the horn on the steering wheel started "sticking" about 2 years ago. But it doesn't make any noise, you can just either feel the button or it's flat. Lately though the car horn just starts blaring. Usually when I unlock the car and press on the horn it stops.

The last couple of times though it would not stop. I tried unlocking the car, pressing the horn while it was off and then when I tried to turn my car on, it wouldn't start. My neighbor came and tried to help me, but nothing we did stopped it. It eventually stopped after about 15 mins. I don't know if you've ever heard the horn on a Lancer but it is obnoxious! I thought it was the alarm system since he said the reason why my car would not turn on was because the alarm locked the car. I disabled the alarm and I thought that helped. But it just did it again, twice in about 4 hours.

I took my car to my mechanic and he said the only way to see what was wrong would be to remove the airbag. He said he called the dealer and it would have been $800 for a new airbag. I don't go to that mechanic anymore because I got a $450 tune up there and he did a horrible job- he didn't even bother to lube my spark plugs. There are no Mitsubishi dealerships where I live and the closest one is about 2 hours away. I live in a very small town because I go to college, and when I go home, where there is a dealership, it's usually on the weekends for a day or two.

Any suggestions as to what I can do to stop my car horn from doing that?