Start > type cmd in start search > right click “run as administrator”.
Copy and paste the commands below as given in each line (one by one)
net stop wuauserv (hit Enter)
cd %systemroot% (hit Enter)
ren SoftwareDistribution SoftwareDistribution.old (Hit Enter)
net start wuauserv (Hit Enter)
net stop bits (Hit Enter)
net start bits (Hit Enter)
net stop cryptsvc (Hit Enter)
cd %systemroot%\system32 (Hit Enter)
ren catroot2 catroot2.old (Hit Enter)
net start cryptsvc (Hit Enter)
regsvr32 Softpub.dll /s (Hit Enter)
regsvr32 Wintrust.dll /s (Hit Enter)
regsvr32 Initpki.dll /s (Hit Enter)
regsvr32 Mssip32.dll /s (Hit Enter)
Restart the computer. Try Windows Update, Success, Windows update now working.