cannot updat windows

Hello,

About a week ago i noticed that the windows update didn't work (i don't know for how long this already was). It said that the serurity centre wasn't turned on. When i tried to turn it on, i got a error (don't now what anymore, but when i looked at services, the was no item serurity centre). I surfed the internet and tried various things. One of the things was "combofix". Combfix found a virus called Rootkit.ZeroAccess. Combofix maked the repairs. after that i could turn on serurity center, but when i tried to update windows i got the error 80096001. I tried various thing i found on the internet (fixit's from microsoft, different scans), bur with no result.
I use avira internet serurity. There is a problem to that accurred yesterday; only the realtime scanner is active, but not the mail and web protection.
When i look at the action-centre i says that windows defender is not active and i said that i don't have a virus program.
I did everything from the tread "Vista and Win 7 Malware Removal/Cleaning Procedure".

In the Malware forum a got some advise (fix.zip How do I reset Windows Update components? Use the MS Fix it Tool., Windows Repair Tool, How to Run a Startup Repair in Windows 7), but non of it did word. They said that i had to pleace thit tread in this forum.

I hope you can help me. I'm close to the point to back-up the most importent files, format the pc and install windows again, but i hope did isn't nessecarry.

Kind regard,
Fiona

 

Kestrel, thx for the help