I have no sound

I assume you've checked different headphones/speakers that you know work with other audio sources, correct?

if so, one other thing to try would connecting to some audio output device via the dock connector (speaker dock, car adapter etc) -- if you have such thing available. if sound comes out via dock connected speakers then at least you know it's not likely a logic board problem.

otherwise it's probably your headphone jack. you can find the repair guide here

before purchasing a replacement headphone jack, you might first want to confirm that the ribbon cable securely connected to the logic board.