i need help with vauxhall vectra 2.0 dti 16v v reg?

after being very good on deisel my vectra ran out though i still had some according to the gage, after refilling i was able to carry on driving the next day i ran out again so refilled and the car will not start at all i put some more in and it still wont start the battery's fine but does anyone know what the fault could be and how to fix it, thanks,