non starting Audi A6?

my 2001 Audi A6 (1.8Turbo) has been getting worse and worse to start in this cold weather until today when it wouldnt start at all.it turns over as normal and up to today once i got it to start it has been running well too. there is plenty of fuel in tank ,but it just doesnt seem to be firing.

paul jenkins
December 2009