1996 Discovery tdi cut out and now wont fire

Hello,
I'm hoping some of you might be able to help,
my 1996 Discovery tdi cut out and now wont fire, I don't know much about mechanics but have tinkered in the past and got away with it,

So far I have checked all four injectors and fuel is getting to them
the glow plugs have power getting to them and have never been a problem so far
and yes it has fuel in it I have half a tank

if it helps the day it cut out was very cold, and it died after I got to the top of a hill, its automatic diesel

any help or suggestions would be great
Thanks

Welcome.
Is there power getting to the fuel shut off solenoid?