Sorry Pete i haven’t understand what you exactly want.
Is there any solution to fix the problem ? I really don’t know what to do now 
Start by confirming that everything works fine when the Wemos is used alone.
Then provide a wiring diagram of how everything is connected when you have the LCD and anything else connected-up.
Pete.
Hi Pete and thanks again for your patience,
So i confirm you that i tested every single composant, and they works well (even the resistors 220 Ohm each).
here is my wiring diagram . The LCD display is in I2C ( can’t find it in Frizting).
I confirm again that when i unplug the ground the wemos connect easily and stay connected when i re plug the ground, but then the display doesn’t work ( only full squares ).
How are you powering all of this?
Pete.
It is powering with my PC from the USB port.
And usually ( when it works) with a power bank or from electrical outlet through a phone charger for example.
( Do you ever have a day off or you never sleep? thanks for all)
Try powering the LCD from a separate 5v supply, but keep the ground connection between the Wemos and LCD.
If you’re actually doing this on a breadboard then that may also be where your problem lies. Breadboards are notorious for poor connections.
Every day is a day off for me 
Pete.
Hi Pete Thanks for your answer again,
I have a lot of work, i’ll try it, i think, tomorrow ( if i can manage some rest) and i let you know the results.
Thanks again
from the picture you provided of your wiring scheme, you appear to have D3 (GPIO 0) pulled LOW. This i one of the “special” pins on the ESP. pulling it LOW upon powering up puts it in flash mode, thus no wifi connection. Try using a different pin like D5 (GPIO 14) or D6 (GPIO 12).
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I’m not sure how you are getting it to work while connected to your computer. Your line “Blynk.begin(auth, ssid, pass);” is suggesting that the Blynk library command is both setting up your wifi and authenticating with Blynk. Which begs the question of why the ESP8266WiFi library is defined.
Might I suggest the following for your initial part of your void setup() routine.
void setup() {
Serial.begin(9600); // Setup Serial port
WiFi.begin(ssid, pass); // Connect to WiFi with defined parameters
while (WiFi.status() != WL_CONNECTED) { // Wait until connected
delay(500); // 1/2 Second delay while things connect
Serial.print(F("*")); // Still alive pulse while you connect
}
Blynk.config(auth); // set Blynk authentification string
Serial.print(F(“Connecting to Blynk…”)); // send to serial what it’s doing
Blynk.connect(); // starts the Blynk connection.
From there I would expect things to go more smoothly…
Hi Toro_Blanco, Hi Pete,
I would like to thank you, you fixed the problem, I changed to pin 3 for pin 5 and it works great.
Thank’s again a lot you fixed it.
And thanks Pete for the time you spent for me.
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Hi jhale716,
Thank you for your answer, actually it works with this sketch and because i am a beginner with Blynk ( not with arduino) and its special sketches i will not change it ( i am so afraid do to others mistakes).
But i noted what you wrote , i i’ll try it next time if i meet this kind of connection problems.
Thank’s again for your kindness.