need help

ok i had a dx civic and wrecked it. so i took my apexi n1 off it and put it on my 2000 civic ex i also had an airmass header i put on the ex too. but the header is shot so i took it off but during the process of putting the n1 the o2 sensor on the bottom of the car in the floorboard which was in the resonator was stripped out so i just cut it to put the new mid section on and now my speedometer doesn't work nebody know y is it cause of me cutting the o2 sensor or something different ne help will be appreicated