If you have updated to Windows 10 and it has failed or is not working, try the following steps-
1. Boot into safe mode - Shut down your computer and wait 5 seconds after turning off before plugging in power again.2. Open Command Prompt3. Type stop wuauserv4. Type wuauclt refresh, this will initiate a refresh of your cached updates5. Restart PC6. Let Windows install all the updates7.: Make sure you are connected to WiFi otherwise downloads might take long