Very basic questions - you are hooked up to a working 30 amp service - correct? If you're on a 15 amp circuit you can't draw enough juice to run an a/c. Second, are you sure you reset the breaker? On mine, you have to turn the breaker hard OFF before it will successfully reset.
Last - temperature. Presuming you have a thermostatically controlled unit, if it's 65 outside and the thermostat is set to 75... the A/C won't come on. First - try "fan only" to see if that will operate. If not, you may have wires loose or disconnected somewhere. At this point I call in a professional, but if you have more knowledge of electricity and a/c others may advise checking voltages, etc.
Today is a gift, that's why they call it the present.