Arduino Uno R3 USB is not working
You could try to flash the firmware of the USB controller.

General steps for Arduino R3 are:


Put the Arduino in DFU mode (the R3 does not require soldering for that)
Flash the firmware using:

dfu-programmer atmega16u2 erase
dfu-programmer atmega16u2 flash Arduino-usbserial-atmega16u2-Uno-Rev3.hex
dfu-programmer atmega16u2 reset


The package "dfu-programmer" is most likely available for your distribution.


If you have to build it from source, because your DFU programmer does not know the ATmega16U2 yet, you will need to install libusb-dev (on Debian-based systems).

Useful links for that:


Resetting your Uno R3's default firmware
Updating the Atmega8U2 and 16U2 on an Uno or Mega2560 using DFU


A useful search term for that is Arduino R3 DFU-programmer.