Hi Cecile,
Thank you for sharing your question. I understand that you're getting a No audio device installed message on your laptop, and your mic and speakers aren't working. Lets sort this together.
Based on my knowledge this is because your audio drivers are missing or messed up, or it can happen after a Windows update or when you change something on your computer. Since you've already checked and the sound seems off, here's how you can try reinstalling it.
First, right-click the Start button and open Device Manager. Check under Sound, video and game controllers. If there's no audio device there, click View and then Show hidden devices. Still nothing? Go to Action and click Scan for hardware changes. This tells Windows to look for your sound hardware.
If the device shows up but has a warning sign, right-click it, pick Uninstall device and restart your PC. Windows should put the driver back on automatically. If that doesn't work, you can get the newest audio driver from your laptop maker's website.
May I also ask did you installed any updates or changed anything before this started? Knowing that might give us a clue. Also, if you know your laptop model, I can help you find the exact driver you need.
I hope this answer is helpful, if you have any questions, feel free to reply.
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Best Regards,
Noel