Jeep Grand Cherokee Laredo (2000) will not start

So im a fairly new driver and I have had a jeep since the end of august. I drove it several days ago, but yesterday I went to start it and it would turn over but a couple seconds later shut off. Also the gas gauge refuses to to work and says the tank is empty. We have tried charging the battery and putting more gas in it but it still it will not start and shows I have no gas. We also have checked for a leak and there is no signs of a leak. PLEASE HELP.