Windows 8 update Canceled Auto matically .......... how to reinstal it ?

If this is the only instance where you have received this error, then it might simply be an instance where Windows Defender had already updated itself automatically in the background and no longer needed the update.

Check Windows Defender manually.
Open your start screen and simply type
Defender
Select it from the list (Windows Defender)
Select the "Update" tab and check
Virus definition version: 1.181.59.0
and
Spyware definition version: 1.181.59.0
Yours might vary slightly in the numbering.
Click the update button to confirm you have the latest.