May we know the model of the laptop you're using with the headphone? Please do try these troubleshooting steps that may help as well.
- First is to uninstall/reinstall the Sound card driver.
- Open Device Manager and uninstall the Sound card driver.
- Once done, reboot the laptop and it should reinstall the driver automatically.
- After the reboot, do test the headphone again and see if it will be detected or not.
- Next to try is a different headphone or an external speaker and see if that will work.
- If all these will not work then it's a hardware problem meaning the actual 3.5mm ports and a repair will be required inorder to fix it.