Why is usb plug not working

First thing before you do anything deeper: USE A BETTER CABLE, not Chinesium Amazon garbage -- doesn't need to be OEM for Apple or your phone's OEM if Android, but use a good cable like Anker or Best Buy Essentials. I would see if there is a reset button command, or a pinhole switch -- I don't think there will be a pinhole reset option, but disconnecting the battery for 1 hour will reset it but also reset modules like the TCM so it will drive rough until it relearns.

Failing that I'd check the fuse - I don't have a Forte OBDII/fuse cover available to show you, but it's usually under the accessory or cigarette lighter fuses as they tend to get tied together a fair bit on Kia/Hyundai chassis. USB is different enough it should be a dedicated fuse, but I would double check and see. I do not like to use the visual method and check the fuse with a DMM like this: https://www.lowes.com/pd/Klein-Tools-Dig... -- just as a precaution, I would change them out to be safe as they might have a partial failure. It's likely a fuse and they typically label these "MULTIMEDIA" -- most Hyundai/Kia chassis use 10A but check to be sure -- it may also be the 15A Navigation unit fuse.

If it keeps occurring, I would check the ports for damage and depending on if it is USB-A or USB-C, get a tester tool and see what type of readings you get -- if you get low volts and low amps, the issue likely lies with the module or a Hyundai electrical gremlin. I would replace the module and that will usually fix it as the Hyundai gremlins typically do not happen there, they usually happen somewhere else. But it's also not unheard of either. The module can be found here: https://www.kia.parts/oem-parts/kia-usb-... -- that said, use that part number at KiaPartsNow and it might be cheaper, I've used them and they sell the real deal for sometimes a much better price.