Check the microphone's USB cable is connected to your computer. It's a common mistake to disconnect the microphone to free up USB space and forget to plug it back in. Try using a different USB port if the computer doesn't recognize the microphone as expected.
Make sure the switches on the side of the microphone are in the correct positions. Select "Inst/Mic" on the "Input" switch if you are recording using the microphone or connecting a mono instrument to the computer via the G-Track. Choose "Line" if you are connecting a stereo musical instrument. Select "Mono," "Stereo" or "CPU" using the "Direct Monitor" during playback, depending on your needs.
Adjust the three volume control dials on the front of the microphone, making sure none are completely turned down. The computer might not detect a signal from the G-Track if the volume controls are not in the correct position. The "Mic" dial adjusts the microphone's sensitivity to sound.
Make sure your computer system sound is turned up. In Windows, click the speaker icon in the system tray in the bottom right corner of the screen and drag the slider up. Click "System Preferences" from the dock on a Mac, then click "Sounds." Drag the microphone slider to the right to increase the volume.
Verify any musical instrument connections; a loose cable could cause a recording problem. Make sure everything connected to the G-Track is working correctly. Check your external amp if you don't use your computer speakers and cannot hear playback.