public string GetApplicationPath()
  {
   string applicationPath = "";

   if (this.Page.Request.Url != null)
    applicationPath = this.Page.Request.Url.AbsoluteUri.Substring( 
     0, this.Request.Url.AbsoluteUri.ToLower().IndexOf(
      this.Request.ApplicationPath.ToLower(), 
       this.Request.Url.AbsoluteUri.ToLower().IndexOf(
      this.Page.Request.Url.Authority.ToLower()) + 
      this.Page.Request.Url.Authority.Length) + 
     this.Request.ApplicationPath.Length);
  return applicationPath;
  }

Use this in any ASP.NET page to get the application path. For example, if you run this function in http://localhost/pathtest/test.aspx, the function will return http://localhost/pathtest/

Another way to redirect is to use the .NET tilde. For example, to navigate to the home page of your website from any place, you would do Response.Redirect(“~”); or even ~/default.aspx.