Installing updates gets to 30%, restarts and reaches 75% then "We couldn't complete the updates, undoing changes" but no error code.
Ok, after spending all day with this finally got it fixed, downloaded the standalone KB2919355 package and made a note of the install order. Changed windows update settings to prevent automatic update as a precaution. Ran "Dism /Online /Cleanup-Image /RestoreHealth" (without the quotes) from elevated command prompt, rebooted and ran "sfc/scannow" (again without the quotes) from elevated command prompt and received no errors.
Disconnected from the Internet then uninstalled all peripheral drivers, Logitech keyboard and mouse, joysick drivers, Nvidia drivers, soundcard drivers, chipset and usb drivers. Checked all drivers in device manager and uninstalled any that were not Microsoft's own like IDE, HID and network ticking the box to delete driver if available rebooting where necessary.
Checked windows update history and made a note of any updates that said "without KB2919355" and uninstalled through Programs and features (could not uninstall KB2961908).
Installation instructions state "KB2919442 is a prerequisite for Windows 8.1" but received error "not for your system" so did not install. Installed the standalone KB2919355 package in order and rebooted after each one, the first time installing KB2919355 it got to 30% again then rebooted into windows but in windows update history KB2919355 showed requires reboot, after installing KB2932046 and rebooting KB2919355 showed succeeded. Installed the rest and Installed updated drivers for sound video mouse etc, now receiving proper updates again, phew.
You may not need all these steps but better to be safe.
Good luck, Reg.