Powershell to web

Question

Hello guys,

I try to create a Web page for end users to change their own password alone in active directory.

I used Powershell script in C #. When I executed the code, the following error appears [Incomplete ParseException: The Terminator "is missing in the chain.]

 help please!!

Thank you!!

NB :I have to work with Powershell.

using System;
using System.Management.Automation;
using System.Text;

namespace PowerShellExecution
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void ExecuteCode_Click(object sender, EventArgs e)
        {
            // Clean the Result TextBox
            ResultBox.Text = string.Empty;
            // Validate the input
            var usr = user.Text;
            var op = oldpwd.Text;
            var np = newpwd.Text;
            var np1 = newpwd1.Text;
            // Initialize PowerShell engine

            using (PowerShell shell = PowerShell.Create())
            {
                string pwdScript = "Set-ADAccountPassword -Identity \"" + usr + "\"  -Oldpassword  \"" + op + "\"  -NewPassword \"" + np ;
                {

                    shell.AddScript(pwdScript);
                    // Execution du script
                    var results = shell.Invoke();

                    if (results.Count > 0)
                    {

                        var builder = new StringBuilder();

                        foreach (var psObject in results)
                        {

                            builder.Append(psObject.BaseObject.ToString() + "\r\n");
                        }


                        ResultBox.Text = builder.ToString();
                    }
                }
            }
        }
    }
}