1997 yukon ran fine until i turned it off

I have a 97 yukon 5.7 and i got up in the morning started it, let it run for a while, drove to the gas station, pulled up to get gas, killed it, and filled up. It was running fine but when i got back in and tried to start it it wouldnt start. I have checked all fuses and relays, put gas down the throttle body, checked fire... cant figure out whats wrong. any help?