Windows Defender Disabled - Will Not Enable

Hello,

It took me a while to finally get back to working on this issue. The issue is happening on my personal laptop and now that I have a self built desktop computer I haven't been using the laptop much.

I performed the deletion of the folder in the registry and rebooted as directed. I am still unable to get the Defender antivirus to work. It is still showing as disabled in the services and all options to try to start it are greyed out/inaccessible.

Before I do the in-place upgrade from the directions you suggested I wanted to ask some questions. I have some custom Defender Firewall rules set up; will the in-place upgrade delete them? What about all of my installed programs? Will it render them no longer viable/working requiring they all be reinstalled? I also have a NAS with multiple folders mapped through Windows; will I need to re-map them?

If the answer is yes to any or all of the above questions, is there any other option other than the in-place upgrade?

Thank you.

Unfortunately, the Independent Advisor you were originally connected with is only attached to the thread for a few days, after which if the thread goes inactive for some period, it's dropped from his notifications, and he'll only see this if he manually looks back through past threads. I assume that's happened to yours.

Since I'm just a volunteer, I use the typical method of viewing recent threads and just happened to read yours out of curiosity, so I'll do what I can to help first before suggesting you start a new thread.

This article includes the following in the Key Takeaways, section.

"An in-place upgrade allows you to reinstall and upgrade Windows without losing your personal files, apps, and settings."

How to Repair Windows 11 With an In-Place Upgrade (and Keep Your Personal Data)

However, it also mentions early in the article that the in-place upgrade can change many things on the computer and could possibly go wrong, so they recommend creating a backup.

I've seen this option suggested many times here since though it obliterates most significant issues with things like damaged or modified Windows components, it still leaves personal apps, files and settings alone, which is what most people care about in these situations.

However, based on what it does I'd assume it's going to reset not only the Windows files, but also likely any settings made within the core Windows components like Defender and the Firewall in order to repair them, so those are items I'd expect to be at potential risk when using In-Place Upgrade.

If you don't have a way to back these up and restore them separately from the entire Windows image, then you'd probably be better re-starting a new thread and referring to this one with a short description of the current status, since anyone can look here for reference.

There are a number of known attacks against Windows Defender that can disable it as you clearly understood before starting this thread, so there are at least as many ways to repair it.

I don't personally keep track of these since as a retired network administrator and security professional myself, I bought a Surface Go tablet running Windows 10 S Mode a few years ago specifically to avoid these sorts of issues that are completely unnecessary to use the apps any typical consumer truly needs today. It's the legacy business apps that create all of the problems.

< EDIT > FYI, I just saw an article with search about exporting Firewall rules in Windows 10 so you can import them later, so that issue may be easily solvable.

The question of the NAS is less clear to me, but if I were you, I'd probably want to know if something similar were possible there, since being able to restore these if a system were damaged might be valuable.

Good luck.

Rob