Hi, I was loading normally a code to the card, I guess something went wrong, suddenly went on the computer the message Unrecognized Device, now whenever I connect get this message and RX LED is lit, the plate if turned on, but the computer does not recognize.
I await your valuable help, Regards.
To load a new sketch on your Leonardo:
Hold the reset button and continue to hold while selecting Upload.
When the IDE shows Uploading...
Release the reset button.
Try this with Blink or some other known good sketch.
Truly thank you very much, thank you've solved the problem, I thought that the card had been broken.
Thank you for taking the time to help me, Regards.
Thank you very much, this should be included in the official troubleshooting section!
I had the same problem: Something went wrong during the upload of a sketch with the result that the USB device, i.e. the Arduino Leonardo, was not recognized by Windows 7 (32bit) anymore. The green LED ("ON") was lighting up, but the Rx or Tx LEDs didn't blink. Thought the bootloader was corrupted and I need to buy an ICSP programmer to fix it but this simple trick solved the problem.