Nodemcu ESP8266 can't connect to Network

Hi everyone ,

I have NodeMcu Esp8266 , I try to connect it to My network and it isn't done

I did it before and it connected but it unable to connect again

I tried to scan WIFI networks and it done ( the result is : it works correctly and it find all wifi networks around )
but the main problem it doesn't connect to any WIFI Network

The Following is my code ( Note : I tried this code on another one NODEMCU ESP8266 and it works correctly )

#include <ESP8266WiFi.h>

WiFiServer server(80);

WiFiClient client;

String myresultat;
String ClientRequest;
String ReadIncomingRequest(){
while(client.available()) {
ClientRequest = (client.readStringUntil('\r'));
 if ((ClientRequest.indexOf("HTTP/1.1")>0)&&(ClientRequest.indexOf("/favicon.ico")<0)){
myresultat = ClientRequest;
}
}
return myresultat;
}

void setup()
{
Serial.begin(9600);

  WiFi.disconnect();
  delay(3000);
  Serial.println("START");
  WiFi.begin("MYNetwork","MY123456");
  while ((!(WiFi.status() == WL_CONNECTED))){
    delay(300);
    Serial.print("..");

  }
  Serial.println("Connected , My IP Address Is :");
  Serial.println((WiFi.localIP()));
  server.begin();

}


void loop()
{

    client = server.available();
    if (!client) { return; }
    while(!client.available()){  delay(1); }
    Serial.println((ReadIncomingRequest()));
    client.println("HTTP/1.1 200 OK");
    client.println("Content-Type: text/html");
    client.println("");
    client.println("<!DOCTYPE HTML>");
    client.println("<html>");
    client.println("Welcome");
    client.println("</html>");
    client.stop();
    delay(1);

}