How do I code the release of a momentary touch sensor in IDE?
You have a semicolon that doesn't belong in your code. Your current code (With the indentation cleaned up a little)

void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // print out the value you read:
  Serial.println(sensorValue);
  if(sensorValue &gt; 100) {
    Serial.println(F("Playing track 001"));
    musicPlayer.playFullFile("/track001.mp3");
  }
  else(sensorValue &lt; 100); { // &lt;&lt;&lt;--semicolon does not belong here.
    Serial.println(F("Paused"));
    musicPlayer.pausePlaying("/track001.mp3");
  }
}


Should be:

void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // print out the value you read:
  Serial.println(sensorValue);
  if(sensorValue &gt; 100) {
    Serial.println(F("Playing track 001"));
    musicPlayer.playFullFile("/track001.mp3");
  }
  else(sensorValue &lt; 100) { // &lt;&lt;&lt;--semicolon removed from this line
    Serial.println(F("Paused"));
    musicPlayer.pausePlaying("/track001.mp3");
  }
}


With the semicolon after the else, your code reads "...else do nothing" and then I would expect it to execute the pause logic no matter what value is in sensorValue. 

You should pick an indentation style and then be absolutely consistent with it. Most C/C++ programmers use K&amp;R style, which is what I used in my edit. (Opening braces are on the same line as the if statement/function that begins the scope, code inside braces is indented, and closing brace is at the same indentation level as the line that contains the opening brace.)