I see your up in Maine, sounds like it's a fuel problem. Where do you get your fuel? In the winter cold, it's a must to run off road fuel that is cut for the winter. I also add anti gel additive in it. Most heating oil companies sell it and sometimes propane suppliers. Do you have a block heater? If not that's a must have.
Best thing to do is thaw out the tractor with a torpedo heater. If the tractor isn't in a shelter that cant easily be heated up, drape a big tarp over it and throw some weight on the edges of the tarp. Put the heater under the tarp carefully not to ignite anything on fire and turn that into a hot air balloon. Let it flambé for a few hours to thaw out and then give it a try.
Chances are fuel is gelled up even if you use an additive in regular pump diesel. I would also change the fuel filter before starting. Throw that starting fluid away, that will cook your diesel motor quick! With A block heater and good fuel that tractor should start up with no problems.
