arduino suddenly shows "avrdude: ser_open(): can't open device "\\.\COM3" after last upload

Question

I am using arduino uno to make a sound detector. I uploaded a program, found error in the code that it returns unintended numbers unreasonably big. I also think I used wrong code for the module, but it was connected in the way that can work properly with the proper code.

The code I uploaded was:

const int ledPin =13;
const int middleValue = 512;
const int numberOfSamples =128;

int sample;
long signal;
long averageReading;

long runningAverage = 0;
const int averagedOver = 16;

const int threshold=400;

void setup(){
    pinMode(ledPin, OUTPUT)
    Serial.begin(9600)
}

void loop(){
    long sumOfSquares = 0;
    for (int i=0; i<numberOfSamples; i++){
        sample = analogRead(0);
        signal = (sample - middleValue);
        signal *= signal;
        sumOfSquares += signal;
    }
    averageReading = sumOfSquares/numberOfSamples;
    runningAverage=(((averagedOver -1 )*runningAverage)+averageReading)/averagedOver;

    if(runningAverage>threshold){
        digitalWrite(ledPin, HIGH);
    }else{
        digitalWrite(ledPin, LOW);
    }
    Serial.println(runningAverage);
}

When the arduino suddenly stopped sending serial numbers, I pressed reset button and uploaded the default code:

void setup() {
}

void loop() {
}

but now it shows that it cannot connect to COM3 (arduino) and cant find the device, When I can see arduino uno successfully connected to PC using device manager (windows 8.1). The led light of arduino also turns on when I connect it to power source or usb.

it shows "port not found" when I click to see the serial output

Did I just fry Arduino? How should I fix this?

Also, i checked the led pin 13 blinking three times when i plug in the usb. I just cant upload anything

Answer 1

What worked for me:

Tools>Port>(your COM)

Just selecting that solved the error.

Answer 2

You should do a few checks in order to jump to a conclusion, your Arduino may be just fine. As far as I know, Code cannot destroy a controller.

1. Check if any other software is using the same serial port. Two softwares cannot use the same serial port at the same time
2. Restart your PC and then try again
3. Remove the Microcontroller from the board, connect it to the PC and try to open the com port. If it opens then connect your Tx pin with the Rx pin, send some data and check if you are getting the data back. This way you will ensure your USB-TTL converter is fine
4. If this goes successful, then insert your microcontroller in some other board and check if it is getting programmed

I am sure after these checks you will find out the reason of the failure of your board/microcontroller.