You  will have to use both technique .
MediaStore and file explorer .
public class MainActivity extends ActionBarActivity {
private File file;
private List<String> myList;
private ListView listView;
private TextView pathTextView;
private String mediapath = new String(Environment.getExternalStorageDirectory().getAbsolutePath());
private final static String[] acceptedExtensions= {"mp3", "mp2",    "wav", "flac", "ogg", "au" , "snd", "mid", "midi", "kar"
    , "mga", "aif", "aiff", "aifc", "m3u", "oga", "spx"};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    listView=(ListView) findViewById(R.id.pathlist);
    pathTextView=(TextView) findViewById(R.id.path);
    myList = new ArrayList<String>();   
    String root_sd = Environment.getExternalStorageDirectory().toString();
    Log.e("Root",root_sd);
    String state = Environment.getExternalStorageState();
    File list[] = null ;
    /* if ( Environment.MEDIA_MOUNTED.equals(state) || Environment.MEDIA_MOUNTED_READ_ONLY.equals(state) ) {  // we can read the External Storage...
        list=getAllFilesOfDir(Environment.getExternalStorageDirectory());
    }*/
    pathTextView.setText(root_sd);
    file = new File( root_sd ) ;       
    list = file.listFiles(new AudioFilter());
    Log.e("Size of list ","" +list.length);
    //LoadDirectory(root_sd);
    for( int i=0; i< list.length; i++)
    {
        String name=list[i].getName();
    int count =     getAudioFileCount(list[i].getAbsolutePath());
   Log.e("Count : "+count, list[i].getAbsolutePath());
   if(count!=0)
   myList.add(name);
        /*int count=getAllFilesOfDir(list[i]);
        Log.e("Songs count ",""+count);
        */  
    }
    listView.setAdapter(new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, myList ));
    listView.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int position,
                long arg3) {
            File temp_file = new File( file, myList.get( position ) );  
            if( !temp_file.isFile())        
            {
                //LoadDirectory(myList.get( position ));
                file = new File( file, myList.get( position ));
                File list[] = file.listFiles(new AudioFilter());
                myList.clear();
                for( int i=0; i< list.length; i++)
                {
                    String name=list[i].getName();
                    int count =     getAudioFileCount(list[i].getAbsolutePath());
                       Log.e("Count : "+count, list[i].getAbsolutePath());
                       if(count!=0)
                      myList.add(name);
                    /*int count=getAllFilesOfDir(list[i]);
                    Log.e("Songs count ",""+count);
                    if(count!=0)
                        myList.add(name);*/
                }
                pathTextView.setText( file.toString());
                //Toast.makeText(getApplicationContext(), file.toString(), Toast.LENGTH_LONG).show(); 
                listView.setAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, myList ));
            }
        }
    });
}
private int getAudioFileCount(String dirPath) {
        String selection =MediaStore.Audio.Media.DATA +" like ?";
        String[] projection = {MediaStore.Audio.Media.DATA};    
        String[] selectionArgs={dirPath+"%"};
        Cursor cursor = this.managedQuery(
            MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
            projection,
            selection,
            selectionArgs,
            null);
        return cursor.getCount();
  }
@Override
public void onBackPressed() {
    try {
        String parent = file.getParent().toString();
        file = new File( parent ) ;         
        File list[] = file.listFiles(new AudioFilter());
        myList.clear();
        for( int i=0; i< list.length; i++)
        {
            String name=list[i].getName();
            int count =     getAudioFileCount(list[i].getAbsolutePath());
               Log.e("Count : "+count, list[i].getAbsolutePath());
               if(count!=0)
              myList.add(name);
            /*int count=getAllFilesOfDir(list[i]);
            Log.e("Songs count ",""+count);
            if(count!=0)*/
        }
        pathTextView.setText(parent);
    //  Toast.makeText(getApplicationContext(), parent,          Toast.LENGTH_LONG).show(); 
        listView.setAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, myList ));
    } catch (Exception e) {
        finish();
    }
}
// class to limit the choices shown when browsing to SD card to media files
public class AudioFilter implements FileFilter {
    // only want to see the following audio file types
    private String[] extension = {".aac", ".mp3", ".wav", ".ogg", ".midi", ".3gp", ".mp4", ".m4a", ".amr", ".flac"};
    @Override
    public boolean accept(File pathname) {
        // if we are looking at a directory/file that's not hidden we want to see it so return TRUE
        if ((pathname.isDirectory() || pathname.isFile()) && !pathname.isHidden()){
            return true;
        }
        // loops through and determines the extension of all files in the directory
        // returns TRUE to only show the audio files defined in the String[] extension array
        for (String ext : extension) {
            if (pathname.getName().toLowerCase().endsWith(ext)) {
                return true;
            }
        }
        return false;
    }      
}
}
.xml file :
<LinearLayout   xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
    android:textSize="21sp"
    android:typeface="monospace"
    android:id="@+id/path"
    android:layout_width="fill_parent"
    android:layout_height="100dp"
    android:layout_margin="10dp"
    android:gravity="bottom"
    android:text="PATH : " />
<View
    android:layout_width="fill_parent"
    android:layout_height="2dp"
    android:background="#111111" />
<ListView android:id="@+id/pathlist"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
</ListView>
 </LinearLayout>
Permissions in manifiest file :
 <uses-permission  android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>