The first thing is to check the Inertia switch. A good thump can trigger it and it cuts off the power to the fuel pump(s). In trucks it's usually located on the passenger side of the firewall, inside the cab. Simply push the button on top to reset, if it's already down then that wasn't the problem.
Assuming you have plenty of fuel, next you need to check for fuel pump activation. Take off the gas cap and either (a) listen at the tank while a helper turns the key on which activates the pump for about 2-3 seconds which you can hear or (b) if you have no one available to help, stick a hose into the tank filler (just a little way is fine, not all the way down in the fuel) and listen at the other end of the hose while you turn the key on yourself.
If you're not sure you heard it, turn the key off and then on again. Each time it will cause the pump(s) to run briefly.
If you don't hear the pump, check the fuel pump relay (usually under or around the Power Distribution Box under the hood.)
Check these items and get back to us. If all is good there but you're still not getting fuel, we can give you a few more things to check.