Board used to work, now it doesn’t. That’s bad.
Check that your other board works with the same cable.
Does the other board also have the same serial adapter chip? (16u2 for official and some clones, ch340g for most clones; the former has a few rarely used extra capabilities, while the latter is cheaper and harder to blow)
If you’ve confirmed that the same computer can see the working uno but not the non-working one, with the same cable, and they both use the same serial adapter IC, you trashed the serial adapter IC; this cannot be repaired without hot air rework capability and experience using it, and even then it’s so much effort it’s not worth it. Throw it out and buy a new one.
I recommend CH340G clones, as they are harder to damage (the 16u2 is pretty easy to burn out by abusing the power rails - inductive spikes from motors without snubbing diodes can do it, as can some as-yet-unclear situation involving external power (which may be something that’s supposed to work, or may be some easy mistake - all I know is that almost all the people here who trash their 16u2 - and there are kind of a lot of those people - were either using an external power supply or driving motors) - I’m honestly rather unhappy with the decision of Arduino to use the 16u2 as serial adapter, because these boards are designed for electronics newbies, but the 16u2 is much easier than other usb serial adapters to damage with newbie mistakes.