I have a 19.5 42inch deck riding mower and no gas

Sounds like you might have a bad fuel pump or it is sucking air in the fuel sysyem.take a air hose and force air into gas tank and see if line is leaking fuel.if so change fuel line where it is leaking.

disconnect fuel line from fuel filter, snake fuel line over to left side of engine. Remove gas cap and fuel will empty out of fuel tank.

it should have a gas tank under th seat and it has a fule pump that pulls the gas up to the carb that dosent mean the pump is bad you may need a carb kit

check fuel line for colapse near frame rail common problem ? new hose from tank to fuel filter will fix it

THE V-TWINS HAVE AN EXTERNAL FUEL PUMP AND IS GRAVITY FED FROM THE TANK TO THE PUMP. MAKE SURE THE FUEL LINE IS IN GOOD SHAPE AND THE FUEL LINES ARE BELOW THE FUEL TANK LEVEL ANT TIME THE FUEL LINE GETS ABOVE THE FUEL LEVEL IN THE TANK FUEL WILL STOP FLOWING TO THE FUEL PUMP CAUSING THIS PROBLEM

Have the fuel lines or engine shielding been modified at all? Has the fuel filter been changed?
If all of that is OK, remove the fuel line from the tank at the fuel pump, remove the fuel fill cap, gently blow air back through the fuel line so you can here bubbles in the tank. The "tank pre-filter" could be plugged.
Let me know.
Regards,

check to see if there is a fuel pump diaphram first and rebuild or replace it , otherwise you arent getting any vacuuum in the carb to draw the fuel in.

It has a screen filter inside the tank that may have gummed up.If you drain the gas and look inside the tank,You will be able to see it.