i have define code  File selectedFile = new File(selectedFilePath); when run and test is it file or not  
 if (!selectedFile.isFile()){

        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                tvFileName.setText("Source File Doesn't Exist: " + selectedFilePath);
            }
        });
        return 0;

        it give message source file does't exist; why give this message, i have allready convert

        full code 
         public int uploadFile(final String selectedFilePath) {

    int serverResponseCode = 0;

    String file_name = selectedFilePath;

    HttpURLConnection connection;
    DataOutputStream dataOutputStream;
    String lineEnd = "\r\n";
    String twoHyphens = "--";
    String boundary = "*****";

    int bytesRead,bytesAvailable,bufferSize;
    byte[] buffer;
    int maxBufferSize = 1 * 1024 * 1024;
    File selectedFile = new File(selectedFilePath);

    String[] parts = selectedFilePath.split("/");
    final String fileName = parts[parts.length-1];

    if (!selectedFile.isFile()){
      //  dialog.dismiss();

        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                tvFileName.setText("Source File Doesn't Exist: " + selectedFilePath);
            }
        });
        return 0;
    }else{
        try{
            FileInputStream fileInputStream = new FileInputStream(selectedFile);
            URL url = new URL(SERVER_URL);
            connection = (HttpURLConnection) url.openConnection();
            connection.setDoInput(true);//Allow Inputs
            connection.setDoOutput(true);//Allow Outputs
            connection.setUseCaches(false);//Don't use a cached Copy
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Connection", "Keep-Alive");
            connection.setRequestProperty("ENCTYPE", "multipart/form-data");
            connection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
            connection.setRequestProperty("uploaded_file",selectedFilePath);

            //creating new dataoutputstream
            dataOutputStream = new DataOutputStream(connection.getOutputStream());

            //writing bytes to data outputstream
            dataOutputStream.writeBytes(twoHyphens + boundary + lineEnd);
            dataOutputStream.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename=\""
                    + selectedFilePath + "\"" + lineEnd);

            dataOutputStream.writeBytes(lineEnd);

            //returns no. of bytes present in fileInputStream
            bytesAvailable = fileInputStream.available();
            //selecting the buffer size as minimum of available bytes or 1 MB
            bufferSize = Math.min(bytesAvailable,maxBufferSize);
            //setting the buffer as byte array of size of bufferSize
            buffer = new byte[bufferSize];

            //reads bytes from FileInputStream(from 0th index of buffer to buffersize)
            bytesRead = fileInputStream.read(buffer,0,bufferSize);

            //loop repeats till bytesRead = -1, i.e., no bytes are left to read
            while (bytesRead > 0){
                //write the bytes read from inputstream
                dataOutputStream.write(buffer,0,bufferSize);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable,maxBufferSize);
                bytesRead = fileInputStream.read(buffer,0,bufferSize);
            }

            dataOutputStream.writeBytes(lineEnd);
            dataOutputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

            serverResponseCode = connection.getResponseCode();
            String serverResponseMessage = connection.getResponseMessage();

            Log.i(TAG, "Server Response is: " + serverResponseMessage + ": " + serverResponseCode);

            //response code of 200 indicates the server status OK
            if(serverResponseCode == 200){
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        tvFileName.setText("File Upload completed.\n\n You can see the uploaded file here: \n\n" + "http://coderefer.com/extras/uploads/"+ fileName);
                    }
                });
            }

            //closing the input and output streams
            fileInputStream.close();
            dataOutputStream.flush();
            dataOutputStream.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(MainActivity.this,"File Not Found",Toast.LENGTH_SHORT).show();
                }
            });
        } catch (MalformedURLException e) {
            e.printStackTrace();
            Toast.makeText(MainActivity.this, "URL error!", Toast.LENGTH_SHORT).show();

        } catch (IOException e) {
            e.printStackTrace();
            Toast.makeText(MainActivity.this, "Cannot Read/Write File!", Toast.LENGTH_SHORT).show();
        }
      //  dialog.dismiss();
        return serverResponseCode;
    }

You have a complete path for the file, but you discard everything apart from the file name. So it will look for that file in the default directory. In all probablility the default directory is not the same as the one in the original path, so the it's looking in the wrong place.

You can print all that out to confirm.