If the catalytic converter is bad would that cause the car not to start? Thank you

Why do you think it might be bad? Does it smell like rotten eggs? What problems have you had with it? A loss of power from about 80 km/h, less gas mileage?
Are your spark plugs filed? Do you need a tune up?

if the catalytic converter is bad would that cause the car not to start? thank you
No ,it could be your fuel pump or timing chain belt,oryou need plugs and wires.

if the catalytic converter is bad would that cause the car not to start? thank you
It shouldn't prevent the vehicle from starting.
If the converter is bad, it could affect performance, particularly after it has heated to operating temperature.
What year, make, model and engine is your car?
You may want to test the battery and starter, ignition and fuel system first.
Tell us more, please...

The simple answer, as others have said, is no. Like Rich said, we need more information to help you figure out what's going on.