My Car will not start, the key wont turn at all

You won't know much until you get the computer scanned for trouble codes. Most auto parts stores will scan for free in hopes of selling you some parts.

if the other light is ok and the fuel gauge is only dead, may be you have no more fuel, try to refill fuel, if the battery is also dead replace new battery.

crank shaft sensor just had this prob its located on top of trans

To Larry Crowley,
Did you ever correct the problem to your 2000 Jeep Grand Cherokee and did you in fact determine that the problem was in fact the Body Control Module (BCM)?
I too have a 2000 Jeep Grand Cherokee Ltd with 162,000 miles. Up until just a few months ago, I never had any major problems with the car however in early December one evening the car was turned off and parked in my garage and the horn just went off out of nowhere, a solid horn...it was deafening! We unplugged the battery for the night so it wouldn't drain the battery. The next day I took the car to the mechanic who replaced the horn switch and relay. We thought that had fixed the problem. An hour after I left the mechanic with the car both the BRAKE and ABS lights on my dash went on and my speedometer stopped working (very scary to drive that way). When I stopped the car and went to lock it with my keyfob, the solid horn went off again so obviously the problem was not the horn switch and relay!?!? Over the past few months I have had my car to three different mechanics as well as the Jeep dealer and they have all concluded that the problem must be the BCM but they said that the only was they can properly diagnose the car is if it is acting up with the above mentioned symptoms while in the shop. Unfortunately it only acts up intermitently, not all the time. I am at such a loss. Currently we have removed the fuse for the horn so I am driving with no horn which is extremely unsafe! I look forward to any advice you have in this regard. Thank you!

Replace the neutral safety switch.

The key needs to be replaced. Sometimes, not all, for some reason the key is not detected and your vehicle will not start. If you have a spare try it, if not you will need to go to dealership.

Sounds like the ECM....the computer that controls all the electrical functions on the car is having some major issues or needs to be replaced. A auto repair or auto parts store should have a diagnostic machine that will tell you for sure or you can purchase one for between $50 and $150

Try replacing the engine relay switch. It is located under the hood with the other relays. If not check the wires for ground. Check the battery cables , especially the cable that goes to the positive of the starter.

fuse -link bad

burn it!!!!!!