Hey guys, I'm new here so forgive me if I ask stuff in a wrong way.. I need help with something.
I have a code to enable my LED 7 segment display to count to 9 and restart from 0 again. However, I now need to provide an input from the serial monitor which will begin the count all over again from 0 regardless of which number it is at. Any ideas or editing I could do to my code? Please be patient with me, I am new to the programming world 
My code for the count is given below. I tried beginning the serial in the setup and putting some if statements but did not do it successfully. Kindly advise how I could achieve my task. Thanks
/*
- This program counts from 0 to 9 on the LCD display
- Goes from 0 to 9 and back down to zero
- Authors: Fahmid Chowdhury and Maxim Selvamanoharan
- Version 1.1
- Last updated by Fahmid Chowdhury
The circuit:
- 5V voltage supply for the LED
- Output is using digital pins 7 to 13
*/
// Pins connected to LED display
// give the pins an individual name:
int a = 12;
int b = 13;
int c = 9;
int d = 8;
int e = 7;
int f = 11;
int g = 10;
// the setup routine runs once when you press reset:
void setup() {
// initialize the digital pins as an output.
pinMode(a, OUTPUT);
pinMode(b, OUTPUT);
pinMode(c, OUTPUT);
pinMode(d, OUTPUT);
pinMode(e, OUTPUT);
pinMode(f, OUTPUT);
pinMode(g, OUTPUT);
}
// the loop routine runs over and over again forever:
void loop() {
zero(); //Name of the output which is displayed
delay(1000); //duration that the number is displayed for
one();
delay(1000);
two();
delay(1000);
three();
delay(1000);
four();
delay(1000);
five();
delay(1000);
six();
delay(1000);
seven();
delay(1000);
eight();
delay(1000);
nine();
delay(1000);
eight();
delay(1000);
seven();
delay(1000);
six();
delay(1000);
five();
delay(1000);
four();
delay(1000);
three();
delay(1000);
two();
delay(1000);
one();
delay(1000);
zero();
delay(1000);
}
void zero(){ //Name of output defined
digitalWrite(a, LOW); // turn the LED to display 0
digitalWrite(b, LOW);
digitalWrite(c, LOW);
digitalWrite(d, LOW);
digitalWrite(e, LOW);
digitalWrite(f, LOW);
digitalWrite(g, HIGH);
}
void one(){
digitalWrite(a, HIGH); // turn the LED on to display 1
digitalWrite(b, LOW);
digitalWrite(c, LOW);
digitalWrite(d, HIGH);
digitalWrite(e, HIGH);
digitalWrite(f, HIGH);
digitalWrite(g, HIGH);
}
void two(){
digitalWrite(a, LOW); // turn the LED on to display 2
digitalWrite(b, LOW);
digitalWrite(c, HIGH);
digitalWrite(d, LOW);
digitalWrite(e, LOW);
digitalWrite(f, HIGH);
digitalWrite(g, LOW);
}
void three(){
digitalWrite(a, LOW); // turn the LED on to display 3
digitalWrite(b, LOW);
digitalWrite(c, LOW);
digitalWrite(d, LOW);
digitalWrite(e, HIGH);
digitalWrite(f, HIGH);
digitalWrite(g, LOW);
}
void four(){
digitalWrite(a, HIGH); // turn the LED on to display 4
digitalWrite(b, LOW);
digitalWrite(c, LOW);
digitalWrite(d, HIGH);
digitalWrite(e, HIGH);
digitalWrite(f, LOW);
digitalWrite(g, LOW);
}
void five(){
digitalWrite(a, LOW); // turn the LED on to display 5
digitalWrite(b, HIGH);
digitalWrite(c, LOW);
digitalWrite(d, LOW);
digitalWrite(e, HIGH);
digitalWrite(f, LOW);
digitalWrite(g, LOW);
}
void six(){
digitalWrite(a, LOW); // turn the LED on to display 6
digitalWrite(b, HIGH);
digitalWrite(c, LOW);
digitalWrite(d, LOW);
digitalWrite(e, LOW);
digitalWrite(f, LOW);
digitalWrite(g, LOW);
}
void seven(){
digitalWrite(a, LOW); // turn the LED on to display 7
digitalWrite(b, LOW);
digitalWrite(c, LOW);
digitalWrite(d, HIGH);
digitalWrite(e, HIGH);
digitalWrite(f, HIGH);
digitalWrite(g, HIGH);
}
void eight(){
digitalWrite(a, LOW); // turn the LED on to display 8
digitalWrite(b, LOW);
digitalWrite(c, LOW);
digitalWrite(d, LOW);
digitalWrite(e, LOW);
digitalWrite(f, LOW);
digitalWrite(g, LOW);
}
void nine(){
digitalWrite(a, LOW); // turn the LED on to display 9
digitalWrite(b, LOW);
digitalWrite(c, LOW);
digitalWrite(d, LOW);
digitalWrite(e, HIGH);
digitalWrite(f, LOW);
digitalWrite(g, LOW);
}