If you are trying to update Windows 8 and it is spending a long time doing nothing and showing 0% downloaded and 0KB downloaded then follow the instructions below to check what is really happening:
1) Open the Task Manager.
2) Choose the Performance tab and check if anything is happening in the Ethernet section.
3) At the bottom of the Performance window is a link to Open Resource Monitor, click on this.
4) Choose the Disk tab and expand the section Disk Activity.
5) Click on the Write (B/sec) column to sort by files most written to.
6) If you see any files containing the path C:\Windows\SoftwareDistribution\Download\... then Windows update is working fine but it is not showing the correct downloaded percentage or KB in the Windows Update screen.
7) Leave it to do its work and eventually it will progress from Downloading to Installing updates.
Click to check if Windows 8 Update download is working
Windows 8 Update downloading show 0%