Light LED when 2 others are disconnected I need to make circuit in which orange LED will light only when yellow and red are disconnected. When one of buttons is pushed orange LED should turn off.

See my attempt at it below.

I am new to electronics so your help is very appreciated.



EDIT:

After many atemps I managed to build this circuit as on left side of schematic (tested on live breadboard)



but my primary goal is to make this work with RGB LED. I took Common Anode RGB LED for this and build circuit on right side of schematic. I do not have such RGB LED to test it live so I ask you to review if that schematic will work as it has few changes to one with 3 LED's. Thank you

SOLUTION:

Thanks to Bruce's help my circuit now works. 

3 separate LEDs emulate common anode RGB LED (as I do not have one to test circuit)
Q2 is BC 560B transistor with CBE type pinout





CODE:

void setup() {
  pinMode(2,INPUT);
  pinMode(4,INPUT);
  Serial.begin(9600);
  digitalWrite(2,HIGH);
  digitalWrite(4,HIGH);
}

void loop() {
  Serial.println(digitalRead(2));
  Serial.println(digitalRead(4));
}
You want the green LED to be on only when the red and blue LEDs are both off. In other words, you want the voltage on the green LED to be LOW only when the voltages on the red and blue LEDs are both HIGH. That is a logical NAND function.

Your right-hand circuit with the RGB LED won't work because the transistor's collector is connected to the wrong place - it's shorting out the battery! Another problem is that the Arduino can only switch to Ground or +5V, so it can't replace a 'floating' switch. 

You need a configuration that produces a logical NAND function. Your left-hand circuit is doing it, but won't work with a common anode RGB LED. So swap the transistor to a PNP  type, and add a couple of resistors to switch it on when either input goes low, like this:-