To fix sound not coming out of your headphones:
1. Click Start>Control Panel>Hardware and Sound>Manage Audio Devices.
2. Under the Playback tab, select the headphones and set them as default.
3. Verify that the headphones are set as the default playback device.
4. Clean the headphone jack to remove any debris.
5. If using a laptop, right-click the Sound icon, go to playback devices, and select headphones.
By following these steps, you should be able to resolve the issue of sound not coming out of your headphones.