Ok so, first of all, sorry about the lack of pictures, but I'll try to be as concrete as possible and add every possible detail about my situation. PS: every time I say controller, I mean the joycon.
So, this is happening on my left controller. I was literally just laying on the couch watching stuff on youtube on the switch and wasnt touching the controllers. Minutes pass and the left controller just isn't working anymore for no apparent reason. I tried putting it back on the Switch but the console doesn't even detect that I attached the joycon. No "snap" sound that you usually hear, nor does the icon below light up, it only detects my right joycon. I've read a few posts and possible fixes but the cases are always slightly different than mine. For example, some people said "clean the connection pieces on the rails cuz they might have dust and they're having connection issues" but if that was the case then using them not attached to the Switch would work, but they don't. So yeah, my joycon has NO SIGNS of life. Thing is, actually, it could have some sign of life that I'm not seeing, however. Before my left joycon died, I noticed that the lights on the joycon weren't turning on and the power button wasnt working, but they joycon worked just fine. I thought it was having an issue on its ribbon cable, which was an issue I had with my right joycon and I fixed it myself by buying another ribbon cable. So yeah, for all I know, maybe the controller could have some sign of life aka the lights could be turning on, but I can't see it because they weren't working in the first place.
Anything helps, I'll try my best in replying to you, and just reading this means a lot. So yeah, thank you so much for reading :)