I had problems with Arduino uno and reseted firmware. Followed this tutorial. Now I can't upload my code Arduino IDE says:
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00
I tried loop-back mode, everything is fine.
Firmware was located in
/usr/share/arduino/hardware/arduino/firmwares/atmegaxxu2/Arduino-COMBINED-dfu-usbserial-atmega16u2-Uno-Rev3.hex