If your USB port stops working, it might be because of dirt stuck in the USB port or because the USB port is old or worn out and needs to be changed. In cases of dirt being stuck in the USB port, all you need to do is to clean the USB port with a soft brush, isopropyl alcohol, a wet cotton swab, and a container filled with compressed air. If the port still doesn't work after this, then you need to take it to a professional to get it changed.