The left side of the headphones does not work when plugged into my monitor.

[kennedydab]

Hi. Earlier this afternoon when I turned on my computer, only the right side of my headphones was working. I tried unplugging my headphones and plugging them back in. Restarting my computer, the normal things. Nothing was working. I unplugged my headphones and connected them to my phone via Bluetooth (the headphones are Bluetooth but my computer doesn't have Bluetooth so I use a headphone jack cable to connect my headphones to my monitor) and I could hear out of both sides of my headphones properly. Then, I grab a different pair of earbuds and plug those into the monitor and I can still only hear out of the right side of those earbuds. So obviously my headphones, niether the cable is what's not working. So I was wondering if there are any suggestions for what to do, because I've tried looking at videos and none of them are helping me.
Another thing, I tried openeing the sound system on my control panel in settings (I use Windows 10) and when the headphones were unplugged and I tested the audio, both speakers on the monitor worked perfectly fine. So I'm wondering if the Audio Out jack is the problem. Anyway, I'm not exactly sure and I'd really appreciate any suggestions!