my car wont start please help!?

what happened i changed the electrics unit from behind the steering wheel ( where stalks + clock-spring .etc is ) now the car wont start but still turns over perfectly it just the engine wont engage also i have noticed the radio + clock/ temperature display + full beam headlights + taillights are also not working. i have checked all fuses below steering wheel and all are ok none blown also radio fuse on back of radio not blown. also there is no warning lights displayed on dash apart from the usual before starting all the usual lights go out engine warning lite / fuel /oil .etc car is a w reg Renault Meganne coupe 1.4 16v petrol. know this is my own fault but i really need help as recently lost my job and have no cash for a mechanic im really struggling financially rite now thanks to anyone who can help Andrew