Can any one please help!!!

I have a ford Fairmont BA Ghia 2002
I had to take out the stereo to fix a problem with my air con, but when I put the stereo back in I keep getting System Code Error. Is there any way I cn fix this error without taking my car to Ford as I can't afford to?

If the display is reading 'Security Code Error' or similar, try turning the ignition on fully or starting the car, if you haven't already. This usually fixes the issue when the car thinks the ICC doesn't belong to it, like the older stereos that needed a pin code entered. The ICC needs to talk to the rest of the car to know it is in the right vehicle before it will work.

Assuming this is the problem of course. This works when I get the Security Code Error on my BA.