So at work there was an update last night and this morning a lot of critical services cant be accessed due to a requirement for a security certificate.
Beware of the current update!
Using OS Windows 7.
We've explored this to a considerable degree in some other fresh threads. And I agree: Win 7 Windows Update has become "problematical."
The answer you seek -- if that's the meaning of your post -- is in those threads.
There are two KB update files that need to be downloaded directly from the MS web site. Don't know the exact file-names, but you want to install the KB______612 file first. I think that's the update to Windows Update Client.
After that, install the KB______739 file, also downloaded directly and then run locally to install.
After that, be patient while Update "checks for updates." don't interrupt it.
If it takes more than a few hours (at most!), you might still have a problem. But give it time.