Why wont my 1997 Saturn sl1 start?

hey, I Ow a 1997 saturn al1 4 door sedan, it has a 1.9, ok the car ran great before, ok this is the story, my cuzin came down and we were talking about stuff. then i said hey dusty can you tell me what this blinking thing is on the dash board of my car? he said yeah lets see it, ok i started the car, it ran great, like normale it allways starts with no problem, now i turned it off and he said get me a paper clip, i got him on and he put 2 ends into this black thing by the gas pedal and brake, ((( the thing auto zone puts there tester ))) and mest with it, then he said turn hr on and lets see what happens, now i tired turning her on but she wouldnt do anything, like when you turn the key half way on it shows the lights and everythng works fine, but when you go to turn it over like turning it on it wont do anything, the lights stay on but nothing, all the fuse's are fine, box fuse box's are fine, what is wrong with my car? also the horn and dom light stoped working also after this, thanks