public static void playSystemSpeaker(int repeat, int freq, int msDuration)
 {
     try
     {
         for (int i = 0; i < repeat; i++)
         {
             WinAPIHelper.Beep(freq, msDuration);
         }
     }
     catch (Exception ex)
     {
         throw ex;
     }
     finally
     {
     }
 }
        public static WindowsImpersonationContext impersonateValidUser(String userName, String domain, String password)
        {
            WindowsImpersonationContext impersonationContext;

            WindowsIdentity tempWindowsIdentity;
            IntPtr          token          = IntPtr.Zero;
            IntPtr          tokenDuplicate = IntPtr.Zero;

            if (WinAPIHelper.RevertToSelf())
            {
                if (WinAPIHelper.LogonUserA(userName, domain, password, WinAPIHelper.LOGON32_LOGON_INTERACTIVE, WinAPIHelper.LOGON32_PROVIDER_DEFAULT, ref token) != 0)
                {
                    if (WinAPIHelper.DuplicateToken(token, 2, ref tokenDuplicate) != 0)
                    {
                        tempWindowsIdentity  = new WindowsIdentity(tokenDuplicate);
                        impersonationContext = tempWindowsIdentity.Impersonate();
                        if (impersonationContext != null)
                        {
                            WinAPIHelper.CloseHandle(token);
                            WinAPIHelper.CloseHandle(tokenDuplicate);
                            return(impersonationContext);
                        }
                    }
                }
            }
            if (token != IntPtr.Zero)
            {
                WinAPIHelper.CloseHandle(token);
            }
            if (tokenDuplicate != IntPtr.Zero)
            {
                WinAPIHelper.CloseHandle(tokenDuplicate);
            }

            return(null);
        }