why has vista stopped automatic updates?

Thanks to Volume Z, it worked for me in the following order:

1) Followed VZ instructions; 'Set automatic updates to "Never check for updates" and reboot prior to manual installation.'

[Control Panel --> Windows Update --> Change settings --> Never check for updates (recommended)]

2) Downloaded all 5 updates to a local folder on PC.

3) 

Installed KB4019204.

Installed KB4012583.

Installed KB3205638.

Installed KB4015380.

4) Restarted PC.

5) Installed KB4018271 (IE9). 

6) Restarted PC (again).

7) Enabled Windows Update (Control Panel --> Windows Update --> Change settings --> Install updates automatically (recommended). Also, 'Download but let me install' and 'Check for updates but let me do download/install' might be OK?).

7a) Launched Windows Update (Start --> Windows Update). 

It did not initially work. But gave an error message (sorry, can't recall exactly).

Windows own troubleshooting/fix did not help. 

(Perhaps, should have enabled Windows Update before reboot in step 6 or rebooted PC between steps 7 and 7a? i.e Restart after enabling Windows Update and before launching Windows Update... for the changes to take effect??)

7b) Cleaned registry with CCleaner (Registry --> Scan for Issues/Fix selected Issues... and Cleaner --> Analyze/Run Cleaner).

9) Restarted PC.

10) Launched Windows Update (again).

Voila!

This time it worked. Showed 145 Updates to install.

In short, saved me hours, if not days, of going in circles or even resorting to Restore.

Good Luck.

PS; WinVista Home Premium 32-bit, SP2.

Background: 

Windows Updated Microsoft .NET Framework 4.5.1 and Realtek AC'97 Audio. But the PC clock was wrong - a year too fast. 

As a result, Windows Update showed last updates in history as Aug 2019 instead of Aug 2018. 

Then stuck at checking... Also showed, "Windows Update can't check for updates" on Quick Luanch bar.

Of course, first corrected PC time (right-click on time/clock on Quick Launch --> Adjust Date/Time --> Change date and time ... OK). Also, checked BIOS settings, CMOS battery etc before manual downloads/installs.