I recently noticed that my Windows 7 PC (64-bit) had not updated itself for a long time. When trying to manually run Windows Update, it would only open a dialog box saying:
"Windows Update cannot currently check for updates because the service is not running"
This happened despite the fact that the Windows Update service was, in fact, running and also properly configured as Automatic (Delayed Start).
After unsuccesfully trying various built-in fixes in Windows 7 and also trying a downloadable Microsoft Fix It pack, I decided to run a Upgrade using the original Windows 7 installation CD. That finally fixed the problem and now Windows Update is functional again.
The procedure to run an upgrade is:
I don't know how much of your custom settings and applications will be overwritten by this operation. I only use Windows 7 casually for gaming so I did not care.