Microphone and speakers have disappeared from sound preferences

Were you using any headphones just before this issue happened, or had any reason to disconnect any internal connections? Or is this just a sudden occurrence? Try running diagnostics at boot by holding down the D key until the globe appears and follow the prompts and see what it says (Have the charger plugged in during this process). I presume SMC & PRAM resets have been tried without any success.

@livfe No, haven't used headphones for years. Always used a bluetooth device. I first noticed the problem one day (a few months ago) when I turned on my MacBook and did not hear the usual startup sound. I thought it had something to do with using bluetooth devices? Removed all devices, no difference. So I have been doing internet searches and trying all the software resets everyone suggested. But about a year ago now, I did have to replace the MagSafe power cable (110v) as I found the one that came with the laptop was extremely hot, both the connection with the orange/green light on it and that whole side of the MacBook to the headphone jack.

@alsadler The correct charger should be an 85w Mag safe II T-Type.. Did you check that the charging port is clean of dirt and debris as this can also make the charger get 'hot' and overheat. A PRAM reset (OPT+CTRL+P+R) and let it boot chime 2x then release, that should make it chime again. I use the same model and the boot chime sometimes has gone away also after using a BT headset, odd yes, Apple thing no doubt.

@livfe So for the charger I went to an Apple authorized store here in Martinique and got the replacement, as soon as I did that the hot plug and left side of MacBook has stopped. I would think the one I had was also Apple as it came with the laptop 6 years ago? I know I've tried the PRAM reset before, and as I said earlier, I don't get those boot chimes anymore so I don't know when 2x has happened?

@alsadler Do the PRAM reset again and keep holing the keys to let it reset 2 or 3x as that usually brings back the chime, which in turn may bring back the speakers in the audio panel. Failing that, the next step I would try would either be a clean install or installing a system to an external drive and boot from that to see if the speakers appear again. If that failed then there is the probability that there may be a board level diagnostic required and a potential professional fix required. If you do go for a clean install, remember to 'select all devices' from the view option in disc utility and erase the drive from the top level. Of course make a backup of your files beforehand as they will all be erased in the process.