Jeep does not work help!!!

Well, I got up today and got in my jeep to goto school, I tunr the key and it just makes noise and doesnt start up. Its not a dead battery noise, but the noise like its trying to start up but never does. I thought it might be flooded, so I went through that process (pressing down the pedal while turning it on and all that crap), but even after doing that when I go to turn it on it still does the same thing. It was running just fine yesterday afternoon when I drove home from school. What could be the problem?

The vehicle is a 97 Cherokee if that matters

I have a 94 sport, I've been told to clean the NSS and replace the CPS. That is my weekend project. Is yours an automatic? Is so try to start it in neutral, sometimes mine will start in park and sometimes I have to put it neutral and sometimes even have to jam the gear shift a few times in park and it will start. But after it starts I'm driving along and it just dies. Have to let it sit about an hour and it'll restart. That's where the crankshaft position sensor is coming in I think. Good luck and let us know.