Listen under the car when someone turns the key on, you should hear the pump in the tank run about 2-3 seconds to pressurize the system.
Look on the fuel rail on top of the motor, there is a service port that may have a plastic cap, under it is a valve just like on a tire. Carefully press on the core, just like letting air out of a tire. If it is pressurized, gas will blast outta there (watch your eyes). If you get a small spit or nothing, you either aren't reaching gas, or the pump may have died if the tank got knocked hard.
How much gas is in it?
If you think the situation I described at the top might apply, and it's low, put a couple of gallons in it.