Mercedes-Benz: diesel 190d wont start

Your message isn't helpful, some details are needed.

How many miles on the engine?
What have you done so far to get it started?
Does it crank?
How well or poorly did it run just before it stopped?
Did you park the car or did it just quit somewhere?
What recent work has been done, if any?

Answer these and you'll get some thoughtful help.