Hi,
First do check in Playback Devices if your headphone is being detected.
- Right click on the speaker icon and select Playback Devices.
- Right click on the headphone if it's listed and select Set Default.
If that doesn't work uninstall/reinstall the sound card driver.
- Go to Device Manager and uninstall sound card driver.
- Right click on the sound driver and select uninstall.
- Reboot your laptop and it should reinstall the driver automatically.
Lastly, if all these steps won't work try performing a System Restore.