expected '}' before '{' token , how to solves this?? is there any solution??

const int tombol_mtr_kanan_1 = 11;
const int tombol_mtr_kiri_1 = 10;
const int tombol_break_1 = 9;

const int tombol_mtr_kanan_2 = 8;
const int tombol_mtr_kiri_2 = 7;
const int tombol_break_2 = 6;

const int IN1Pin = 5;
const int IN2Pin = 4;

const int IN3Pin = 3;
const int IN4Pin = 2;

void setup() {
// put your setup code here, to run once:
pinMode(tombol_mtr_kanan_1, INPUT_PULLUP);
pinMode(tombol_mtr_kiri_1, INPUT_PULLUP);
pinMode(tombol_break_1, INPUT_PULLUP);
pinMode(tombol_mtr_kanan_2, INPUT_PULLUP);
pinMode(tombol_mtr_kiri_2, INPUT_PULLUP);
pinMode(tombol_break_2, INPUT_PULLUP);

pinMode(IN1Pin, OUTPUT);
pinMode(IN2Pin, OUTPUT);
pinMode(IN3Pin, OUTPUT);
pinMode(IN4Pin, OUTPUT);
}

void loop() {
// put your main code here, to run repeatedly:
if (digitalRead(tombol_mtr_kanan_1)==LOW){
digitalWrite(IN1Pin,HIGH);
digitalWrite(IN2Pin,LOW);
}
else
if (digitalRead(tombol_mtr_kiri_1)==LOW)
{
digitalWrite(IN1Pin,LOW);
digitalWrite(IN2Pin,HIGH);
}

else
if(digitalRead(tombol_break_1==LOW)
{
digitalWrite(IN1Pin,LOW);
digitalWrite(IN2Pin,LOW);
}
}

if (digitalRead(tombol_mtr_kanan_2)==LOW){
digitalWrite(IN3Pin,HIGH);
digitalWrite(IN4Pin,LOW);
}
else
if (digitalRead(tombol_mtr_kiri_2)==LOW){
digitalWrite(IN3Pin,LOW);
digitalWrite(IN4Pin,HIGH);
}

else
{
if(digitalRead(tombol_break_2==LOW){
digitalWrite(IN3Pin,LOW);
digitalWrite(IN4Pin,LOW);
}
}
}

you have missing ) and extra } in your code

next time use code tags when posting your sketch

BTW, here is your sketch that 'compiles'

const int tombol_mtr_kanan_1 = 11;
const int tombol_mtr_kiri_1 = 10;
const int tombol_break_1 = 9;

const int tombol_mtr_kanan_2 = 8;
const int tombol_mtr_kiri_2 = 7;
const int tombol_break_2 = 6;

const int IN1Pin = 5;
const int IN2Pin = 4;

const int IN3Pin = 3;
const int IN4Pin = 2;


void setup() {
  // put your setup code here, to run once:
pinMode(tombol_mtr_kanan_1, INPUT_PULLUP);
pinMode(tombol_mtr_kiri_1, INPUT_PULLUP);
pinMode(tombol_break_1, INPUT_PULLUP);
pinMode(tombol_mtr_kanan_2, INPUT_PULLUP);
pinMode(tombol_mtr_kiri_2, INPUT_PULLUP);
pinMode(tombol_break_2, INPUT_PULLUP);

pinMode(IN1Pin, OUTPUT);
pinMode(IN2Pin, OUTPUT);
pinMode(IN3Pin, OUTPUT);
pinMode(IN4Pin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
if (digitalRead(tombol_mtr_kanan_1)==LOW){
  digitalWrite(IN1Pin,HIGH);
  digitalWrite(IN2Pin,LOW);
}
else
if (digitalRead(tombol_mtr_kiri_1)==LOW)
{
  digitalWrite(IN1Pin,LOW);
  digitalWrite(IN2Pin,HIGH);
}

else
 if(digitalRead(tombol_break_1)==LOW)
{
  digitalWrite(IN1Pin,LOW);
  digitalWrite(IN2Pin,LOW);
}



if (digitalRead(tombol_mtr_kanan_2)==LOW){
  digitalWrite(IN3Pin,HIGH);
  digitalWrite(IN4Pin,LOW);
}
else
if (digitalRead(tombol_mtr_kiri_2)==LOW){
  digitalWrite(IN3Pin,LOW);
  digitalWrite(IN4Pin,HIGH);
}


else
{
if(digitalRead(tombol_break_2)==LOW){
  digitalWrite(IN3Pin,LOW);
  digitalWrite(IN4Pin,LOW);
}
}
}

A quick tip. In the IDE put the cursor just after an opening brace. The IDE’s editor will then put a box round the matching closing brace. This is great for finding out if you have missed or got too many closing braces.

It is a shame that the facility to double click on a brace or bracket and have the whole associated code block highlighted was removed a while ago. Highlighting the block eliminated the need to even search for the boxed matching brace

I still think that the compiler could come up with more clear error msgs when a brace is missing somewhere, it would save us all a lot of time.