Radio problems

Hello i'm new to the site and have a problem w/ my 96 jetta gls....about a year ago I helped my dad install an after market sony cd player, and a few months ago it stayed on even after I took the key out, and when I opened the door it make the ding dong noise that I think it makes when you open the door while driving. All I would have to do is remember to turn the power off when I got out! Now just the other day in the morning it worke fine I got in started it up went to turn on the radio on and nothing, and I noticed the ding dong nosie stopped . I was able to take out the cd. Did I blow a fuse?
Before it stopped working I was able to push on the ignition and make it go off and on. Is there a loose connection? I hope this is an easy repair it's been a very quiet ride I miss my music. Thx ~Jesy

I had a very similar problem with my Jetta. Unfortunately, it's probably your ignition switch. If you're having difficulty starting the car (like you have to find a particular way to turn the key or something) it's your ignition switch. Easy, but expensive to fix. it'll run you about $200. But before you run out and spend all that money, check your fuses. I think it's fuse 12 is the radio.