RX doesn't work on ESP8266-E12 AI

AlvaroFacando:
...when i connect everything, the result is the same...

How is everything connected? Take a picture, draw another paint image, or try one of these schematic web sites:

Scheme-It
CircuitLab
circuits.io
CircuitBee

It may never work, though. You may have damaged that pin. (That's the 3rd time I've said that. -_- )

There may be something specific to the ESP8266, I don't know. That would be a question for a ESP8266 forum. They would also want to see your code and your schematic.