A: Please follow the steps:
1. Open the "Device manager" on your computer, to see if any new port appears, if it is normal, what COM port appears after Arduino UNO board is detected.
2. If a new port appears that means the driver is not installed successfully, which need to be installed again, please right click the port and update the driver, then select the installation directory of Arduino: Program Files\Arduino\drivers\FTDI USB Drivers. After updating, reconnect arduino UNO to PC's USB, then check the COM port at the device manger, and then choose the related com port at Arduino IDE "tool", please note the board's type.