Make sure there is diesel in the tank, dont trust the fuel gauge.
You dont say what year/engine code the car has.
Sometimes it's a failed crank sensor (easy and cheap to check/change).
Sometimes the EDC on the pump, which is more expensive/difficult to check/change, but still do-able.
If the pump has failed you may find the cost of repair/replacement more than the car is worth.
It may, of course, be nothing to do with the pump, just guesswork without seeing it and doing proper diagnosis.
derv
January 2011