I have hooked up a ceiling fan that had white/black/green & red wiring to existing wiring of white/black & green. I hooked the green to green, black to black, white & red to the white. Fan works but the light doesn't and the wires were live even with the main circuit breaker off.Would the fact that it was live turned off have anything to do with it or do I need to rewire? It's in a double wide trailer with what I'm going to say is original wiring.

HMMM, never saw a ceiling fan with a red wire. Lighting is blue or blue/white. Unless you know that a white is current carrying(should be marked) you should never connect a white and a red or black wire together. Connect a hot to a neutral and it will trip the breaker. I would disconnect the red from the white and connect it to the black-what happens? BTW, are there 2 or two switches for the fan? What was there before and how was it connected? If the breaker is off and the wire is hot, you either have a defective breaker or a wire pulled from another circuit.

That red wire, is it coming out of the ceiling box or out of the fan?

If the red conductor is from the fan, than that is the supply conductor for the light.

Turn the power to the circuit off, disconnect the white and red conductors.

Reconnect the white conductors together. Now disconnect the black conductors, add the red conductor to the blacks and cap them together.

Turn the power back on. You should now be able operate the fan and light independently by the poull chains or remote.