DirectoryEntry directoryEntry = new DirectoryEntry(ldaPath, domainName+"\"+ userName, Password);

                if (directoryEntry != null)
                {
                    DirectorySearcher searchEntry = new DirectorySearcher(directoryEntry);
                    searchEntry.Filter = "(SAMAccountname=" + userName + ")";
                    SearchResult result = searchEntry.FindOne();
                    if (result != null)
                    {
                        DirectoryEntry userEntry = result.GetDirectoryEntry();
                        if (userEntry != null)
                        {
                            userEntry.Invoke("SetPassword", new object[] { newPassword });
                            userEntry.Properties["lockouttime"].Value = 0;
                        }
                    }
                }