YOu didn't say if you prefered vb.net or C#. You normally would never
need to find this. You could do it with this code however (use a valid
file to test however):
static void Main(string[] args)
{
Process p = new Process();
p.StartInfo.FileName = @"c:\test\test.docx";
p.Start();
Console.WriteLine(p.MainModule.FileName);
Console.WriteLine("OK");
Console.ReadKey();
}