This morning i started my cherokee to warm it up/defrost it, it started great. I then shut it off to see if the ignition key fit the glove box(just bought the jeep and was not sure). When I went to restart it, it turns and turns but will not fire. I put new plugs it and still nothing. It's getting spark and fuel. I don't know why it will not start so suddenly. It ran great the past couple of days. Any help is appreciated.

 

what year is your jeep, is the engine in good looking shape? no missing hoses or vacuum lines,you might try unplugging and replugging the wires going to the crank sensor sometimes that helps!