I'm not an electrician so i would consult one to inspect.
If I understand this correctly, you said the breaker was replace; what used to be one breaker is now two? if so, this is called a half height breaker where they fit two in the location of one. this is where it gets confusing, you say that you have a 120v/20A and a 220V/30A-this cannot be. A 220V would require two positions and you cannot get a mixed amperage breaker as the lower amperage rating would dictate when to trip. Lets assume that it is a 120V/20 (normal for residential with the exception of stoves, dryer, heaters and spa), one of the two switches would be in the center position if the breaker has tripped. To reset a tripped breaker; go from center position to off then to on.
If the breaker is not tripped and you still have no power, check to insure that you do not have a GFCI inline with this circuit. I had a similar problem with a friends house where there was a GFCI in the garage on the same circuit that they forgot to tell me. Without a voltmeter or an electrical tester, troubleshooting whould be difficult.
Hope this helps