Sounds like some of the internal passages are plugged / gummed up. When you are adjusting the idle mixture screws and nothing happens, they are plugged.
First simple thing you can do is remove the idle mixture screws and spray carb cleaner in the holes, then blow the holes out with compressed air. Do this 3 to 4 times to allow some time for the carb cleaner to desolve the gasoline gum in the passages.
Reinstall the idle mixture screws and back them out 1 1/2 turns from the bottom of their threads.
Start up the car, let it warm up for 10 minutes. Have the car idling at around 700 rpm. Now adjust the idle mixture screws one at a time.
Slowly turn the screw in to close off the fuel until the engine starts to stumble, then back off the screw 1 full turn to let the fuel back in again. Do the same for the other screw too.
If you still get no response then the carb is plugged and needs to be dunked in a gallon of carb cleaner overnight.