If it takes 30 minutes to restart you will have time to trace the source of the problem. Take the fuel line off and put a fuel pressure gauge on the line and turn it over to see if you have fuel pressure. If you have pressure take the gauge off and put a hose on and run it to a bottle or can to see if it has volume. Be careful so you don't dump gas on a hot engine and start a fire. If all this checks out put the line back on and tap the carb at the fuel inlet and see if the needle and seat are stuck. Try starting it, if it goes you have found the problem. If it still doesn't start try putting a little gas into the carb and see if it starts. This will get you started.