Thank you for your answer. I did the connections from Rx/Tx and RESET to GND and nothing changes. The pc not recognize it when I connect it to USB (it was COM3)... my Arduino UNO works perfect with the same cable and same USB port (and all the time they worked in this USB port).
I was working with I2C communication between them with power supplies separated... I don't remember something suspicious.
I think ICSP is my only chance,( but I don't know what I need). Thank you and regards