ArduinoUno and SainSmart IIC/I2C/TWI Serial 2004 20x4 LCD

Hello, i cant make it to work.
i have this LCD

And i cant make it work with this program

#include <Wire.h>
#include <LiquidCrystal_I2C.h>


LiquidCrystal_I2C lcd(0x20, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

void setup() {
 
  Serial.begin(9600);  // Used to type in characters

  lcd.begin(20,4);         // initialize the lcd for 20 chars 4 lines and turn on backlight

  lcd.setCursor(3,0); //Start at character 4 on line 0
  lcd.print("Hello, world!");
  delay(1000);
 
}


void loop() {

  
}

When i get the program in the Arduino i only get the first and third line in black squares.

This is only the beginning of the project and im stuck! jajajjajaja
Help me if you know how.
Thank you.

LCD wrong.jpg

I got it right now.

the address was wrong, and that was it.

LiquidCrystal_I2C lcd(0x"Any number", 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

change that into

LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

Thanks, hope this helps somebody.