Check the batteries and go ahead and hook some jumper cables up on the thing it may start then. I had the same trouble a couple of days ago, my truck would crank like hell but no start, I could hear a buzzing sound under the hood when i first turned the key on and through the dash. I hooked up some cables and bam the buzzing stopped and it fired right off. I think it was the glow plug relay not getting enuf power.