'class LCD5110' has no member named 'setContrast'

help i have no clue how to fix ‘class LCD5110’ has no member named ‘setContrast’ here is my code

/*--------------------VenDuino---------------
Vending machine using FULL ROTATION servos.
V0.32 2017 Ryan Bates, RetroBuiltGames.com
copy and paste into arduino sketch
I/O           PIN#
ServoA        ~11
ServoB        ~10
ServoC         ~9
ServoD         ~6
ButtonA         8
ButtonB         7
ButtonC         5
ButtonD         4
LEDready       13
LEDdispense    12
coinInsert     - 3
A0-A4 Nokia5110 LCD
*/
#include <LCD5110_Graph.h>


LCD5110 myGLCD(A0,A1,A2,A3,A4);

extern uint8_t SmallFont[];

const int ServoA = 11;
const int ServoB = 10;
const int ServoC = 9;
const int ServoD = 6;

const int clockwise = 1700;
const int counterclockwise = 1300;

const int ButtonA = 8;
const int ButtonB = 7;
const int ButtonC = 5;
const int ButtonD = 4;

const int LEDready = 13;
const int coinInsert = 12;

long previousMillis = 0;
long intervalIdle = 500;
int LEDreadyState = LOW;

int y1= 0; int y2= 10; //position shifters for LCD txt


void setup() { 
  
  myGLCD.InitLCD();
  myGLCD.setFont(SmallFont);
  myGLCD.setContrast(70);
  
  pinMode(ButtonA, INPUT_PULLUP);  
  pinMode(ButtonB, INPUT_PULLUP);
  pinMode(ButtonC, INPUT_PULLUP);  
  pinMode(ButtonD, INPUT_PULLUP);

  pinMode(LEDready, OUTPUT);
  pinMode(coinInsert, INPUT_PULLUP);
 
  myGLCD.invert(true);
  myGLCD.print("VenDuino", CENTER, 1);
  myGLCD.print("by Ryan", CENTER, 10);
  myGLCD.print("(c) 2017", CENTER, 30);
  myGLCD.drawRoundRect(13, 0, 70, 8);
  myGLCD.drawRect(0, 20, 83, 47);
  myGLCD.update(); delay(1000); myGLCD.clrScr(); myGLCD.update();      }
  
void loop() 
{ 
//--Blink Ready LED---------------------------------------------------
 unsigned long currentMillis = millis(); 
  if(currentMillis - previousMillis >= intervalIdle) { // save the last time you blinked the LED 
   previousMillis = currentMillis; 
  
   if (LEDreadyState == LOW){  // if the LED is off turn it on and vice-versa:
      LEDreadyState = HIGH; 
      
      myGLCD.clrScr(); 
     myGLCD.print("Please insert", CENTER, y1);
     myGLCD.print(" $0.25. ", CENTER, y2);
     myGLCD.invert(false);
     myGLCD.update();      }
    
   else
     LEDreadyState = LOW;
     digitalWrite(LEDready, LEDreadyState);// set the LED with the ledState of the variable:
     y1=y1 +5; y2=y2+5; //shift the text position down
     if ((y1==35) && (y2== 45)) //when the text almost goes off-screen, move it back up
        {y1=0; y2=10; }
  }
  
//---Wait for Coin/Credit---------------------------------------------------------------
while (digitalRead(coinInsert)==LOW) { //if coin inserted stay in servo enable loop
  digitalWrite(LEDready, HIGH);

  myGLCD.clrScr();  myGLCD.update(); 
  myGLCD.print("Please make", CENTER, 0); 
  myGLCD.print(" a selection. ", CENTER, 10);
  myGLCD.drawRect(20, 20, 63, 47);
  myGLCD.drawRect(20, 20, 41, 47);
  myGLCD.drawRect(20, 20, 63, 34);
  myGLCD.update();
  servoEnable();                    } 
}

void servoEnable(){  
 

while (digitalRead(ButtonA) == HIGH || digitalRead(ButtonB) == HIGH ||
digitalRead(ButtonC) == HIGH || digitalRead(ButtonD) == HIGH) {
  
 //---------Servo A----------------------------------------------------
  if ((digitalRead(ButtonA) == LOW) ) {
     for(int i=0; i<2; i++) 
    {digitalWrite(LEDready, HIGH); delay(50); digitalWrite(LEDready, LOW); delay(50); }
    
 myGLCD.clrScr(); myGLCD.print("Vending", CENTER, 0);
 myGLCD.drawRect(20, 20, 63, 47); myGLCD.drawRect(20, 20, 41, 47);
 myGLCD.drawRect(20, 20, 63, 34); myGLCD.print("A1", 25, 24); 
 myGLCD.update();
  
   for(int i=0; i<57; i++)  // change this to adjust +- full revolution
    {
    digitalWrite(ServoA,HIGH);
    delayMicroseconds(clockwise); 
    digitalWrite(ServoA,LOW);
    delay(18.5); // 18.5ms 
    //delay(50); enable this line to slow servo rotation
    }
    break;                            } // when item is dispensed exit loop and return to wait for coin


  //---------Servo B----------------------------------------------------

  if ((digitalRead(ButtonB) == LOW) ) {
    for(int i=0; i<2; i++) 
    {digitalWrite(LEDready, HIGH); delay(50); digitalWrite(LEDready, LOW); delay(50); }
    
 myGLCD.clrScr(); myGLCD.print("Vending", CENTER, 0);
 myGLCD.drawRect(20, 20, 63, 47); myGLCD.drawRect(20, 20, 41, 47);
 myGLCD.drawRect(20, 20, 63, 34); myGLCD.print("B1", 46, 24); 
 myGLCD.update();
 
   for(int i=0; i<57; i++)
    {
    digitalWrite(ServoB,HIGH);
    delayMicroseconds(clockwise); 
    digitalWrite(ServoB,LOW);
    delay(18.5); // 18.5ms 
    //delay(50); 
    }
   break;                            }


  //---------Servo C----------------------------------------------------

  if ((digitalRead(ButtonC) == LOW) ) {
    for(int i=0; i<2; i++) 
    {digitalWrite(LEDready, HIGH); delay(50); digitalWrite(LEDready, LOW); delay(50); }
    
 myGLCD.clrScr(); myGLCD.print("Vending", CENTER, 0);
 myGLCD.drawRect(20, 20, 63, 47); myGLCD.drawRect(20, 20, 41, 47);
 myGLCD.drawRect(20, 20, 63, 34); myGLCD.print("C2", 25, 37); 
 myGLCD.update();
 
   for(int i=0; i<57; i++)
    {
    digitalWrite(ServoC,HIGH);
    delayMicroseconds(clockwise); 
    digitalWrite(ServoC,LOW);
    delay(18.5); // 18.5ms 
    //delay(50);
    }
    break;                            }


  //---------Servo D----------------------------------------------------

  if ((digitalRead(ButtonD) == LOW) ) {
     for(int i=0; i<2; i++) 
    {digitalWrite(LEDready, HIGH); delay(50); digitalWrite(LEDready, LOW); delay(50); }
    
myGLCD.clrScr(); myGLCD.print("Vending", CENTER, 0);
 myGLCD.drawRect(20, 20, 63, 47); myGLCD.drawRect(20, 20, 41, 47);
 myGLCD.drawRect(20, 20, 63, 34); myGLCD.print("D2", 46, 37); 
 myGLCD.update();
    
   for(int i=0; i<57; i++)
    {
    digitalWrite(ServoD,HIGH);
    delayMicroseconds(clockwise); 
    digitalWrite(ServoD,LOW);
    delay(18.5); // 18.5ms 
    //delay(50); 
    }
    break;                            }
                                                                    }   
}

Post a link to where you got the LCD5110_Graph library from. Please use the chain links icon on the forum toolbar to make it clickable. Or if you installed it using Library Manger (Sketch > Include Library > Manage Libraries) then say so and state the full name of the library.

help i have no clue how to fix 'class LCD5110' has no member named 'setContrast' here is my code

Simple. Don't try to call a method that doesn't exist in a class.

Why do YOU think that the class does have that method?