Hi and thanks for reaching out. My name is Bernard an Independent Advisor and a Windows fan like you. I'll be happy to help you out today.
Do you have third party anti-virus? if yes that is normal that you cannot turn it on, if none, you may follow the steps below:
First you need to check if you have work or school account:
Open Settings> Click Accounts> Click Access work or school then disconnect account there, if no account or already disconnected and you have same issue follow the steps below:
You need to get back the default services of Windows defender, you can do it here:
https://www.tenforums.com/tutorials/57567-resto...
Look for Windows Defender Advanced Threat Protection and
Windows Defender Firewall
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
Method 2. Reinstall Windows Defender
Open registry, then go to: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
Then delete Windows Defender folder, then restart the PC and check it again.
If none will work from the above solution I suggest to do an in-place upgrade wherein it will upgrade the device to the latest version and repair all issues without deleting any files.
Note: before doing this make sure to create a restore point: https://support.microsoft.com/en-hk/help/402753...
- go to this link: https://www.microsoft.com/en-us/software-downlo...
- Select Download tool, and select Run. You need to be an administrator to run this tool.
- On the License terms page, if you accept the license terms, select Accept.
- On the What do you want to do? page, select Upgrade this PC now, and then select Next.
- After downloading and installing, it should fix the issue.
Reference: https://www.microsoft.com/en-us/software-downlo...
Note: if you receive error: “This Pc can’t be upgrade, follow the steps below”
Method 1. Go to C:$WINDOWS.~BT\Sources\Panther then delete the file name compatscancache.dat
Then try again or reboot the PC first then try again.
You might not see the folder as it is hidden, make sure to show hidden files first.
Let me know how does it goes and I hope that helps.
Bernard
Independent Advisor