Reset arduino nano after disabling tx/rx I know, i am a bit dummy sometimes and i don't know why i actually did this but here it is. I have an arduino nano and i want it to use an external power via the the Vin port using a 12V external power supply. I thought this would be as simple as replacing the usb power supply by my external 12V power supply on the Vin pin.
But nothing works so i did some digging on the problem and after many tries like soldering the pins 25 and 26 of the FTDI or connect the TX/RX pins to the GND. Concerning that last point, because the TX/RX was still flashing after beeing connected to the GND i have put in my program this two lines to force TX/RX to be disabled and this is my mistake :

digitalWrite(0,LOW);
digitalWrite(1,LOW);


And now what a surprise i can't load a program in my arduino nano anymore even using another arduino to burn the bootloader. And i get this message :

avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x2e
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x2c
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x33
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x38
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x2e
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x33
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x31


I would like to come back to my factory arduino nano and/or enable once again the TX/RX connections ...
After some more tries something actually worked reinitialising the TX/RX pins, but i don't know why really. I wired RX pin to the reset and i loaded an empty code into the arduino, after that i was able to load any program into my arduino again. Problem solved, but why it solved the problem is the question now.