Dear Alfie Munn (MSci (Hons) Physics FT (4))!
Welcome to the Microsoft Community!
First of all, thank you for trying a series of troubleshooting steps. Since you can't find your laptop's built-in microphone in the device manager, it means that the built-in microphone hardware may be damaged. To help you further, I would like to confirm a few key points:
Update and problem time: Can you recall that the built-in microphone stopped working after updating the operating system or installing certain software, or did this problem suddenly appear without any updates or changes?
Hardware check: Have you tried any physical checks, such as checking whether the microphone hole is blocked by dust or whether the microphone switch on the laptop is accidentally turned off?
Here are some possible solutions and further steps:
Check for hardware problems:
Confirm whether there is a physical switch for the microphone hardware on the laptop and check whether it is turned on.
If possible, try using an external USB microphone to confirm that the sound input is working properly to rule out software problems.
Roll back the driver:
If the problem occurred after the update, you can try to roll back the audio driver to the previous version in the device manager. Right-click the audio device, select "Properties", and then select "Roll Back Driver" under the "Driver" tab.
(PS: If you still can't find it, it is recommended that you select Show hidden devices in the device manager to perform the operation. Check whether the corresponding microphone device is displayed in the hidden devices.)
Reset audio service:
Open Command Prompt (Administrator), and then try the following commands to reset the audio service: net stop Audiosrv
net start Audiosrv
BIOS/System Restore:
If you suspect that the system update is the cause, you can try to restore the system to the state before the update, or reset the BIOS to the default settings.
Disclaimer: Microsoft provides no assurances and/or warranties, implied or otherwise, and is not responsible for the information you receive from the third-party linked sites or any support related to technology.
If you are going to modify BIOS Settings, please back up all your personal files first to ensure you do not lose data.
Hardware Diagnosis:
Use the hardware diagnostic tools provided by HP to check whether the microphone is working properly. Usually these tools can be found on the HP support website or pre-installed in the system.
Contact HP Support:
If the above steps do not solve the problem, you may need to contact HP's customer support. Since the built-in microphone is usually part of the laptop, if it is confirmed to be a hardware problem, it may require professional technicians to repair it.
Please provide more information based on your situation so that we can more accurately determine whether it is a software or hardware problem and take appropriate measures.
Thank you for your understanding and support!
I wish you all the best.
Best regards,
Yang.Z - MSFT | Microsoft Community Support Specialist