First, make sure you're actually recording - that's the round dot immediately to the right of the the start button and doing so at a level that will be audible on playback. Assuming that's done, go to song setup, then preferences, then to audio I/O (in/out) settings. Usually , the choice for both is is either your computer (built-in I/O) or your audio box. Beyond that it's equally simple - make sure your computer speakers are turned on and turned up, or that your audio box settings are dialed in correctly and that you've hooked up your monitors or headphones correctly. If you're using monitors, check them to be sure they're powered up, and that the volume controls are turned up.