If Windows update gets hungs and refuses to move, even after running for days, then there is probably a problem.  Try the following:

• Navigate to "services" and set "Windows Update" to manual
• Re-boot the PC so that Windows Update is not executing
• In IE navigate to the URL https://support.microsoft.com/en-us/kb/3050265, download and install
• Re-boot the PC
• Navigate to the URL https://support.microsoft.com/en-us/kb/3050265, download and install again
• Re-boot the PC
• Navigate to the URL https://support.microsoft.com/en-us/kb/3172605, download and install
• Re-boot the PC
• Go to "services" and manually "start" Windows Update
• Go to the Control Panel and select "Check for Updates".  If we are very lucky this should quickly, within 30 minutes, find various updates that need to be applied.

• Alternatively it may be worth trying this recent update that deals with a inconsistency found in the Windows servicing store which may prevent the successful installation of future updates, service packs, and software

  https://www.microsoft.com/en-us/download/details.aspx?id=20858

  And how to reset Windows Update components

  https://support.microsoft.com/en-gb/help/971058/how-do-i-reset-windows-update-components