Windows Defender in Windows 8.1 Will Not Turn On

I had the same problem. I had Windows 8.0 and updated in the new puter to 8.1 as soon as it was available.

I was told as long as you have an anti-virus program, Windows Defender will not work.  I have used only the FREE AVG antivirus and it has worked perfectly. Often alerting me to a threat and asking to eliminate it. I know it is not perfect but it does work in 8.1.

None of the methods to turn on Windows Defender has worked for me, and I heard from a tech 'expert' that the virus encryptwall is attacking puters and locking files for ransom. The tech guy assured listeners that Defender stops that virus, but then also said the attackers had 'hijacked' Tor.

Obviously without knowledge of what Tor actually is, a browser that anyone can download and use to mask location and ID. 

So that leaves me unsure of whether Windows Defender would actually defend against an encryption attack from ransomers. However, like many of you, I would like it to work in conjunction with AVG, but for now, I'll continue with AVG until then.

maxxxam

I don't know if MichaelImport's issue was resolved, But, I went through the same last two procedures posted eg, Method 1: Start the Windows Defender Service Manually & Method 2: Run Windows Defender as Administrator ...

But I still get the " Windows Defender" has been turned off... if you are using another yadi yada yada... and no matter what I try it still comes up.

The only other malware program I run is a second opinion-Hitman Pro program, that I have ran in perfect compatibility with Windows Defender for a year now... suddenly.. something has turned off the Windows Defender... and nothing I can find will allow me to turn it back on manually... automatically, or, as Administrator.

Please advise.

thanks

Nothing works, I guess the program sucks and nobody can fix it, not even Microsoft.

FredKrimmelbein had the correct fix for me after uninstalling Mcafee.  Thank you.

Cannot open Windows Defender by Method 1 or 2.  States it has been turned off by another application.  Please advise.