

For new Linux users it’s best to stick with well established and supported distributions. Then it’s easier to find solutions for common problems.
It’s good practice to look up what the commands do, you enter when you find a solution. Read the man page or other documentation of the command you’re entering. It doesn’t need to be everything, just enough to get an idea what it does.
Also: take notes when you find a problem and how you fixed it. You can go back to them later.
sound and screen dimming
You can’t give a general answer to this. There are several different software stacks for sound on Linux. A typical one goes like this, but can look different.
Kernel - driver - ALSA - PipeWire - desktop environment - application - user
There might be an error at each of these levels.
In the simplest case, it’s a bad configuration, where the volume is set to 0 or mute somewhere in this stack. So try different applications first to play sound, also try playing sound from the terminal. Change volume sliders in different places.
Then go down the stack. Try playing sound with ALSA directly using aplay and speaker-test.
Finally go down to the driver and see if the hardware is detected. Depending if the soundcard is connected via USB or PCI use lsusb or lspci.
Find out the type snd chipset of your soundcard and then search if there’s a driver for Linux already. If you have new or unpopular hardware, it can take a while (a year or two) for a driver to be written, tested, and accepted into the kernel. Then it has to go downstream to the distributions until you get it. So for new hardware you might have to do some additional steps like finding a driver and compiling a kernel yourself.
It’s also worth checking the log files of the audio stack (ALSA, pipewire, or whatever your distro uses).
screen dimming
The stack looks like this:
Kernel - driver - X11/XOrg or Wayland - compositor - Desktop Environment (KDE, Gnome, etc.)
The error might be the keystroke not registering, the desktop not sending the right command, the display driver not supporting dimming, a bad or missing configuration. Again work through the stack. Find out what your distro uses.
Try setting the brightness through the terminal for example.






Depending on the Pi, you will be limited to USB2 speeds.