Windows Update won't install updates

Hi,
First basics:
From an admin command prompt
[Windows key + X, click command prompt (admin)]
chkdsk C: /F
Your PC will need to restart.
Make sure the result is clear or fixed- else do not proceed.
Post back the result, which you can get after a restart as follows:
How do I see the results of a CHKDSK that ran on boot? - Ask Leo!

If clear:
Then try troubleshooting:
In cortana's search box type Trouble and click Troubleshooting
In the Control Panel GUI that opens, click Troubleshoot Windows Updates
Post back the result

If that doesn't help try
Tweaking.com's cautious repair tool (free).
Observe the cautious stages, select only the Windows Update repair and run it.
Test the result and post back.