passat 2003 2.0l petrol won't fire.

Hi 
I'm hoping someone can lead me in the right direction. i have a 2003 passat 2.0 l petrol and for a while it has issues every so often about starting.been parked for a couple of weeks over xmas and when i went to use it it refuses to start.
The epc light and engine management light are both on the dash board.
I have this afternoon changed the crankshaft sensor hoping this was the issue but it still won't start and both lights mentioned before are still lit up on the dash.
Do i need to do something to reset the computer system or could there be something else to course the problem.. Im trying to solve the issue myself or with some help before taking the car to a mechanic.
I would say thank you in advance and any information on this would be gratefully received
cheers
Deano 501

Hi Deano

Sounds like it could be battery related...maybe a reset would cure it...works on my mk4 Golf each time its left for a while and the battery discharges

Let us know how you got on with it

Cheers,  Trevor