Windows 10: Windows Defender service won't start Access Denied

I wanted to install XBOX app but whenever I install it I got the error > looks like something went wrong 0x80073D0A I looked this code and it seems it wants Windows Defender to be on, so I went to check Windows defender but I can't open it, whenever I click it the open with window popup telling me > you'll need a new app to open this windowsdefender link then I tried to check the services for the Windows defender advanced and firewall services but found them set to manual and disabled respectively, whenever I try to start it I get this error whenever I try to switch it to a

:)

 

Audio Service not starting - access denied

My audio service is refusing to start regardless of what I try on Windows 10 1803.

I have attempted the following:

• Re-installing audio drivers
• Updating audio drivers
• A full virus scan
• A disk check
• An SFC check
• Making sure all the dependencies of the Windows Audio Service are running

None of these have succeeded in changing anything.
Whenever I try to start the audio service, I get this error message:




This made me think it is potentially the firewall messing everything up, so I start up Windows Defender and get this error message:




Are these two problems related, and does anyone know how I can fix it?

EDIT:
The Windows Defender Antivirus Service and Windows Defender Antivirus Network Inspection Service are both not running, and when I try to start them I get this error:




I imagine that this is connected in some way but I have no clue how to fix it.

 

Windows Update service is not starting

If you change startup to Manual, can you start? Or please refer to this post:

• Can’t start Windows Update service with “The delayed
  auto-start flag could not be reset. Error: Access is denied”

 

Windows 10 won´t start any program as Administrator

Hello. I´m having this issue since installed one of the latest Windows 10 system updates.

When I try to open any program that requires Administrator confirmation (that screen with the Yes/No question), this dialog won´t appear anymore. The screen background stays darkened and nothing happens.

1. Using Windows 10 Home (x64)
2. My microsoft user account is properly checked
3. I´m the administrator of the PC
4. Already tried do create another administrator user account - same problem, no success
5. Cannot start any program/service that requires administrator authorization (not even regedit)

Please help!