Stopping and starting Windows services is the new “turn it off and back on again" – it is a great way to interrupt services that are running incorrectly, and usually it takes away the pressure of rebooting a business-critical server.
To stop the Windows Update service, go to Start > Run and enter C:\Windows\System32\Net stop WuAuServ
This will stop the Windows Update service. You should now wait a few moments, before proceeding.
Next, reinstall the Windows Update Agent. This can prove difficult, as it already exists on your system. To get around this, use one of the following links, depending on your server architecture:
For x86-based computers (WindowsUpdateAgent20-x86.exe)
For x64-based computers (WindowsUpdateAgent20-x64.exe)
Once downloaded, install the Windows Update Agent – you may find that Windows displays the following dialogue box as a response:
"Install is not needed since windows update agent is already installed."
In this case, right-click the downloaded .exe file, go to Properties and in the file name box amend the file name so it reads:
You should then be able to proceed with installation.
Finally, after installation has completed, go to Start > Run and enter C:\Windows\System32\Net start WuAuServ to restart the service.