RIGHT...
There are about a billion things this could be... to be perfectly honest you really need someone to look at it who knows what there doing... it no good changing things willy nilly!

Here are some basic things you NEED to do first tell me the results and i will hep you as best i can from there.

1. Does the fuel pump prime? (ie buzz the first time you turn the key)
2. remove one of the 12mm banjo nuts from the top of the meetering head that lead to one of the injectors.. does fuel come out under pressure?
3. Does the ignition system spark. remove each lead individually.. put a spark pug on the end of it and get someone to watch as you turn the key each individual lead/plug need to spark properly.

ASSUMING the car does this but still wont start then your in for some fun!