I have a code that adds email id and name in Isolated space. But it is not able to add multiple data. Also, how can I update in case any data was entered incorrectly?

namespace IsoStore
{

    public partial class MainPage : PhoneApplicationPage
    {

        // Constructor
        public MainPage()
        {
            InitializeComponent();
            IsolatedStorageSettings appSettings = IsolatedStorageSettings.ApplicationSettings;
        }


        private void button1_Click(object sender, RoutedEventArgs e)
        {
            IsolatedStorageSettings.ApplicationSettings.Add("email", "someone@somewhere.com");
            IsolatedStorageSettings.ApplicationSettings.Add("name", "myname");
        }

        private void button2_Click(object sender, RoutedEventArgs e)
        {
            textBlock1.Text = (string)IsolatedStorageSettings.ApplicationSettings["email"];
            textBlock2.Text = (string)IsolatedStorageSettings.ApplicationSettings["name"];
        }
    }
}

• windows-phone-7
• c#-4.0

Cleaned up your code a little for you, using a helper method to do the store:

namespace IsoStore
{
    public partial class MainPage : PhoneApplicationPage
    {
        private IsolatedStorageSettings _appSettings;

        // Constructor
        public MainPage()
        {
            InitializeComponent();
            _appSettings = IsolatedStorageSettings.ApplicationSettings;                
        }


        private void button1_Click(object sender, RoutedEventArgs e)
        {
            SaveSetting("email", "someone@somewhere.com");
            SaveSetting("name", "myname");
        }

        private void button2_Click(object sender, RoutedEventArgs e)
        {
            textBlock1.Text = (string)_appSettings["email"];
            textBlock2.Text = (string)_appSettings["name"];
        }

        private void SaveSetting( string setting, string value )
        {
            if (_appSettings.Contains(setting))
            {
                _appSettings[setting] = value;
            }
            else
            {
                _appSettings.Add(setting, value);
            }
        }
    }
}

Try a few other examples to get your head around using IsolatedStorageSettings.

• How to: Store and Retrieve Application Settings Using Isolated Storage
• All about WP7 Isolated Storage - Store data in IsolatedStorageSettings

I have in mind 2 options, you either save your data to isolatedStorageFile MSDN Library OR ,this is what i might do in such case, You save under the key email all your emails as one string separate the emails with a char that is not allowed to be in an email, Coma "," lets say, when needed split your string and retrieve it to whatever makes you comfortable.

private void SaveSetting( string setting, string value )
    {
        if (_appSettings.Contains(setting))
        {
            _appSettings[settings] = _appSettings[settings] + "," + value;
        }
        else
        {
            _appSettings.Add(setting, value);
        }
    }

please note that this code segment is copied from HiTech Magic' answer.