EDIT: I figured my Arduino probably died, and bought a new one. And what do you know, the new one works fine! So yeah, problem solved.
I'm on a 16" MacBook Pro, trying to program an ATtiny 85 through an Arduino diecimila. This has been working just fine for the past several years but a few days ago the USB port simply disappeared from the Arduino port menu. I rebooted my computer and it returned, and all was well.
Until today. I had the same issue, except now, no matter how many times I reboot, the USB port is still missing.
The Arduino does show up in System Profiler as a USB device, so it's definitely communicating with the computer.
I did not update anything whatsoever since it last worked.
What I tried but didn't work: Restarting many times, installing some dodgy CH34x drivers, then removing them, restarting several times again, installing FTDI driver, restarting, removing it, restarting, I tried a different USB cable, two different brands of USB-C to USB adapters, I tried using some old version of Arduino, as well as the newest version (1.8.12).
I tried all my USB ports, and they all work otherwise (tried them with external hard drives and they're fine).
Could not test on another PC yet.
macOS Catalina 10.15.3.
Please help... I'm going crazy, nothing is helping.