Windows Security/Defender won't open

[kitnoman]

So tried to check the group policy and registry editor, repair system image, restore corrupted system files. There's no 3rd party anti-virus. I really don't know when this started, as I've only notice now. I'm also not the only user of this computer.

 

Still getting is:

But it won't apply. I can't even scan a file using the right click. At this point I think I'm about to reformat and reinstall windows. Is there any other option, that I haven't tried?

Edit: looking at service, it seems defender is running and active in the background, but won't launch when I try to open it. It seems that it's the firewall is causing all this issue. The firewall won't enable.