Engine will not start or even fire.

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Did you lay up the tractor with a full fuel tank?
Was the tractor under cover during lay up?
Did you start it up approximately every six weeks and warm it up?

with starting fluid a diesel should do something unless your compression is to low, or the timing is off. does yours have a compression release that could be stuck open . If you can warm the whole engine , if things are a little off that should make it easier to start till things get loosened up.

Had another thought make sure that the fuel shut off that is used to kill the engine is not stuck closed. I was told it is good if once you kill the engine to return the fuel shut off to the run position , reason if the fuel has some moisture in it could cause rust to form and not allow the rail to let the  fuel to flow. You might want to loosen the fuel line at the injector and turn the engine over to make sure there is fuel to that point.