While using ether isn't recommended, it is somewhat OK as long as glow plugs aren't being operated. Not firing with ether isn't good. In nearly any case the engine should pop. If it's not popping then either the valve timing is horribly messed up (like valves stuck open- no compression to ignite the fuel/ether) or it's not getting air.
Fuel, air and compression. Again, if either didn't cause the engine to at least pop then it's not "fuel" (though there could still be issues with the fueling system having an issue which would keep it from running on diesel- fuel shutoff, blocked fuel line or a bad injection pump [or timing]). For compression you'd have to do a compression test; if there hasn't been any previous issues like this then having compression collapse on you all of a sudden is a pretty improbable thing. And speaking of compression, the starter has to spin the engine at a sufficient enough speed to build up compression to ignite; a weak battery and a tired starter (they get arthritic- often cured by pulled apart, cleaning and lubing) can keep a diesel from firing. That leaves AIR... Pop off your air filter hoses and all going into the engine- rodents can plug stuff up pretty well.
Good luck!