How to change Void with button press I have 2 buttons and 2 voids (blink_slow) (blink_fast).
i need to be able to press button 1 and blink-slow void will run, then press button 2  and blink fast will run. none of my code works, any idea how i can do this?

const int btn1 1;
const int btn2 2;
const int led  13;

void setup(){
pinMode(btn1,INPUT_PULLUP);
pinMode(btn2,INPUT_PULLUP);
pinMode(led,OUTPUT);
digitalWrite(led,HIGH);
}
void loop(){
if(digitalRead(btn2 =LOW)){
blink_slow();
}
if(digitalRead(btn3 =LOW)){
blink_fast();
}

void blink_slow(){
digitalWrite(led,LOW);
delay(1000)
digitalWrite(led,HIGH);
delay(1000)
}

void blink_fast(){
digitalWrite(led,LOW);
delay(500)
digitalWrite(led,HIGH);
delay(500)
}
Start by correcting the obvious:

const int btn1 = 2;
const int btn2 = 3;
const int led = 13;

void setup()
{
  pinMode(btn1, INPUT_PULLUP);
  pinMode(btn2, INPUT_PULLUP);
  pinMode(led, OUTPUT);
  digitalWrite(led, HIGH);
}

void loop()
{
  if (digitalRead(btn2) == LOW) {
    blink_slow();
  }
  else if (digitalRead(btn3) == LOW) {
    blink_fast();
  }

void blink_slow()
{
  digitalWrite(led, LOW);
  delay(1000)
  digitalWrite(led, HIGH);
  delay(1000)
}

void blink_fast()
{
  digitalWrite(led, LOW);
  delay(500)
  digitalWrite(led, HIGH);
  delay(500)
}


The mistakes where 1) const variable assignment, 2) using pin 1 (TX) is a potential risk if you later what to use Serial for debugging, etc, 3) condition expression, and a lot of formatting. Open your C/C++ book and check the syntax. 

Now your turn to improve this!