Launching a Desktop Application with a Metro-style app

If you simply want to run a desktop application like (notepad, wordpad, internet explorer etc) then go through Process Methods and ProcessStartInfo Class

try
{
// Start the child process.
    Process p = new Process();
    // Redirect the output stream of the child process.
    p.StartInfo.UseShellExecute = false;
    p.StartInfo.FileName = "C:\Path\To\App.exe";
    p.Start();
}

// Exp 2

// Uses the ProcessStartInfo class to start new processes,
// both in a minimized mode.
void OpenWithStartInfo()
{
    ProcessStartInfo startInfo = new ProcessStartInfo("IExplore.exe");
    startInfo.WindowStyle = ProcessWindowStyle.Minimized;

    Process.Start(startInfo);

    startInfo.Arguments = "www.northwindtraders.com";

    Process.Start(startInfo);
}

On Windows 8 Metro application i discovered this: How to Start a
external Program from Metro App.

All the Metro-style applications work in the highly sand boxed
environment and there is no way to directly start an external
application.

You can try to use Launcher class – depends on your need it may
provide you a feasible solution.

Check this:
Can I use Windows.System.Launcher.LauncherDefaultProgram(Uri) to invoke another metro style app?

Ref: How to launch a Desktop app from within a Metro app?

Metro IE is a special app. You cannot invoke an executable from Metro style apps.

Try this – I have not test yet but may be it will help you..

Launcher.LaunchFileAsync

// Path to the file in the app package to launch
string exeFile = @"C:\Program Files (x86)\Steam\steamapps\common\Skyrim\TESV.exe";

var file = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFileAsync(exeFile);

if (file != null)
{
    // Set the option to show the picker
    var options = new Windows.System.LauncherOptions();
    options.DisplayApplicationPicker = true;

    // Launch the retrieved file
    bool success = await Windows.System.Launcher.LaunchFileAsync(file, options);
    if (success)
    {
       // File launched
    }
    else
    {
       // File launch failed
    }
}