Built-in audio has stopped working in Debian 12.11 on Lenovo P51 Laptop

The sound configuration has spontaneously stopped working on my Linux laptop. I do not know the cause, or how to fix it. ### Symptoms: In the PulseAudio control panel, I can set Built-in Audio to - Analog Stereo Input - Pro Audio - Various Digital Surround... options that all say "(unavailable) (unplgged)" - Off If I use Analog Stereo Input, my laptop microphone works but my laptop cannot play sound. If I use Pro Audio, my laptop can play sound (seemingly at a lower volume than it used to be capable of), but my microphone does not work. I am not sure when this issue appeared, but it most likely entered with a routine apt-get update some time in May of 2025. To my recollection, I have not manually installed any new packages during this time, but it is possible that an unrelated package update has changed the audio configuration. Prior to this, the Built-in Audio device could play audio through the laptop speakers and record audio through the laptop microphone at the same time. This worked out of the box with, for example, video calls, from the day I installed Debian up until a few weeks ago. I did not need to manually adjust any settings for video calls to work. ### System: - Debian (12.11) Linux - Lenovo P51 laptop - Kernel version 6.1.0-34-amd64 - All standard update applied via apt as of 01 June 2025. - Single boot device, no other operating systems. - The system appears to be using PulseAudio, and I have not manually altered the audio configuration since the original (stock) installation of Debian 12 approximately 6 months ago. I have never been very skilled in understanding, diagnosing, debugging, or fixing audio issues in my 20 years of using Linux, so I thank you for your patience and advice in advance. I am not sure what steps to take next to try to fix this.