Sounds like the carb is badly clogged internally. If you can remove it yourself, you can soak it overnight in a can of carb cleaner. But keep in mind some of the internal passageways in the carb are as fine a human hair and soaking may not work, it which case go to plan B, new carb. Last resort you could try to find cleaners small enough to get in the passageways of the carb, I've heard of people using wire brush bristles for example. Today's gas is terrible, it does not take long to gum up the carb, if it sits for any time.