300 tdi wont start please help

hi hope someone can help i have a 300 tdi on a r reg that was driving fine got to work great went to go home that evening and she just turned over but wouldnt start we managed to tow start it but then when i turned it off again it would not start again i have changed the diesel lift pump thinking it was this,however it did start but once turned off didnt start again people are saying it could be just the fuel filter but this has covered less than 1500miles since i last changed could it be sucking in air if so where would i start to look!!!!!!!! HELP I WANT TO PLAY IN THE MUD

try your sedimenter fillter back end of your disco by your tank

hi finally got round to looking at the sediment filter and all has been ok for almost 2 weeks now so i think that was the problem it was like a mouldy jelly inside bloody messy aswell thanks again chris.