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Layback Bear said:

Bertie you have got a lot of good ideas given you but I would like to add a little information.

The Windows 7 built in Defender has been obsolete for a long time.
If you would like to keep with something from Microsoft that replaces Defender use MSE.

Microsoft Security Essentials - Microsoft Windows

When you install MSE it will turn off Defender and MSE will take it's place.
You will be safer with MSE.

You don't need to backup all your data when doing a Clean Install if you don't want to save your data.
If you want to save some data when doing a Clean Install you will have to get some storage device for that data.
The understanding we want you to have is once you do a Clean Install all data on that partition will be lost if it is not backuped.

gregrocker said:

I'd strongly recommend as has Shawn that you Clean Reinstall Windows 7 since you'll never know for sure it's completely clean or undamaged after heavy infection even if the scans come up clean.

If you would prefer to try to repair, and SFC /SCANNOW Command does not show unfixable System Files after 3 tries, and you don't want to run a Repair Install which often fixes problems like this, then try these to see if you can get Updates functioning:

System Update Readiness Tool fixes Windows Update errors in Windows 7
Windows Update - Reset - Windows 7 Forums
Windows Update Posting Instructions - Windows 7 Help Forums

Keep in mind that Windows Update may require plenty of Restarts and even Shutdowns if there are Updates queued with a "!" on the Start Menu Shutdown button. This is how to clear them if they bunch up or start erroring.

Okay, I understand now that it's important to do a clean install. The only problem is: I don't have no external hard drive. And I want to keep some stuff. But thanks for your help with Updater and Defender or MSE, I will try that soon.

It discusses in Step 2 of Clean Reinstall Windows 7 how to upload your files to OneDrive for storage. You get 15gb free storage for each Windows Live ID.