Does not start

You may have not put enough gas in. Most gas tanks have a bowl in the middle and the fuel pick-up screen sits in there. That bowl prevents the gas from running to the side of the tank and away from the pick-up screen when cornering, and the level is low. Once you run out of gas, you need to add enough so the level gets high enough to spill over into that bowl. When I run out with my minivan, the engine will not restart unless I put in at least five gallons.

No spark should not be caused by running out of gas. The only possibility I can think of is the gas is needed to cool the fuel pump. When you run out, the pump could run hot, and it might have blown a fuse. That fuse is often the same one that feeds the ignition system.

Listen for the hum of the fuel pump for one second when you turn on the ignition switch. If you do not hear that, start by checking the fuses inside the car and under the hood.

The next step would be to have your mechanic connect a scanner to read the diagnostic fault codes. If there are any, those will direct him to the circuit or system that needs to be diagnosed. The scanner will also let him fire the injectors individually to see if those circuits are working. The fuel pressure must be checked with a pressure gauge too. If it is too low, the engine won't run.