Programmer is not responding on Arduino Uno

I get this message when I try to upload code in Arduino Uno:
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xef
Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

Please help me.

Remove any connections to pins 0 and 1. These pins are used for communication with your computer, including uploads. Connecting anything to these pins can interfere with uploads.

Make sure you have the correct board selected from the Tools > Board menu.

Make sure you have selected the port of your Arduino board from the Tools > Port menu.

Sometimes the port will be labeled with the board name in the menu. Other times it will not. If you don’t know which port is your Arduino, you can find it like this:

  • Unplug your Arduino board from the computer.
  • Tools > Port
  • Note the ports, if any, listed in the menu.
  • Close the Tools menu
  • Plug your Arduino board into the computer.
  • Tools > Port - The new port listed in the menu is your Arduino board.