You could try the pre-glow plug method of starting but it does strain the
battery if it is not up to scratch.

The method is:

Press throttle to the floor.    Then turn the key to run the starter motor.
After a little while the engine will keep trying to fire and then start to
kick in.   DO NOT let go yet, keep the starter running until the engine
starts to rev.

If that works then your problem is almost certainly glow plug related.   If
it doesn't work, then you may have an air lock in your fuel line that needs
bleeding.   Again, the old fashioned way to do that was to slacken the pipe
connection to the first injector and run the starter.   As soon as fuel
starts to escape from the joint, tighten it and repeat for all injectors.
I believe there are more modern ways of doing it now but that method never
used to fail.