'Start' was not declared in this scope

I'm doing my project with arduino, but I haven't studied this. I did something anyway, and it worked fine, but after I edit some lines, the error message was popped up.
how can I fix this?

here's my code

//motor A control
int IN1=7;
int IN2=6;

//motor B control
int IN3=5;
int IN4=4;

//speed control
int ENA=9;
int ENB=3;

//fsr A, B
int sensorA = A0;
int sensorB = A1;

//buzzer
int speaker = 10;
int G3 = 196;
int C4 = 262;
int D4 = 294;
int E4 = 330;
int F4 = 349;
int G4 = 392;
int A_4 = 440;
int B4 = 494;
int C5 = 523;

int x = 0;
int y = 0;

void setup() {
Serial.begin(9600);
pinMode(IN1,OUTPUT);
pinMode(IN2,OUTPUT);
pinMode(IN3,OUTPUT);
pinMode(IN4,OUTPUT);
pinMode(speaker,OUTPUT);
}

void loop()
{
int valA = analogRead(sensorA);
int valB = analogRead(sensorB);

Serial.println(valA);
Serial.println(valB);

while (valA <10 && valB <10 ){
tone(speaker, C4, 250);
delay(250);
tone(speaker, C4, 250);
delay(250);
tone(speaker, G4, 250);
delay(250);
tone(speaker, G4, 250);
delay(250);
tone(speaker, A_4, 250);
delay(250);
tone(speaker, A_4, 250);
delay(250);
tone(speaker, G4, 250);
delay(1000);
analogWrite(9,25);
analogWrite(3,25);
Start();
delay(1000);
Stop();
for (x = 0; x >= 0; x ++){
int valA = analogRead(sensorA);
int valB = analogRead(sensorB);
Serial.println(valA);
Serial.println(valB);
if (valA >= 10 or valB >= 10){
x=0;
break;
}
}
if (valA >= 10 or valB >= 10){
break;
}
}

while (valA >=10 or valB >=10){

analogWrite(9,30);
analogWrite(3,30);
Reverse();
Stop();
for (y = 0; y>= 0; y++){
int valA = analogRead(sensorA);
int valB = analogRead(sensorB);
Serial.println(valA);
Serial.println(valB);
if (valA < 10 && valB < 10){
y=0;
break;
}
}
if (valA < 10 && valB < 10){
break;
}
}
}

}

//motor A,B clockwise
void Start()
{
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
}

//motor A,B Stop
void Stop()
{
digitalWrite(IN1,LOW);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,LOW);
}

//motor A,B conterclockwise
void Reverse()
{
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
}

int valA = 0;
int valB = 0;

a58936:
but after I edit some lines

But you don't think it's important to say where and what for comparison? Or even post the complete error message?

But a tip, every { needs a single }. You should end up with as many { as } after the last line.

PS Please use code tags next time, see "How to use the forum" for that and many more!

Have you tried to go back step-by-step to see where what you added went wrong? If it compiled before it must be one of the changes that you made, which should be simple enough to rectify.

These 2 lines (currently the last of your file) should be place before setup

int valA = 0;
int valB = 0;

Remove these lines before the void start(): they cause your compile problem.

}

There's a bit more to the error message. The black area below the orange bar in the IDE can be scrolled & resized to see the rest of the error.

Looks like you have an extra } that's throwing out everything after it.

thanks a lot guys! now it's fixed!!!!