Just use following steps
Start/Run ==> regedit.exe
Under the registry key
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
delete the value "NoWindowsUpdate" if it exist.
Under the registry key
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Windows Update
delete the value "DisableWindowsUpdateAccess" if it exist.
Under the registry key
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Group Policy
Objects\LocalUser\Software\Microsoft\Windows\CurrentVersion\Policies\Windows Update
delete the value "DisableWindowsUpdateAccess" if it exist.
If the above values were not found:
Do a registry search (in regedit.exe, be sure to have "My Computer" selected when starting
each search)) for registry values with name
NoWindowsUpdate
and
DisableWindowsUpdateAccess
and delete if found.