Hi Calmat,
Firstly can you bring up "Run" with the following keys: :winkey: + R
Then please type: "Services.msc" press "Ok"
Once Services has loaded please locate "Windows Defender Services" double checkin and make sure that it is start type is "Automatic" and that it is "Started". You will see what this looks like on a screenshot below. After that please bring up Windows Defender and check that it says across it "Your PC is being monitored and protected" and everything is green
shown below:
Once you have checked everything is running lets bring up task scheduler.
Again bring up a run :winkey: + R and enter "taskschd.msc /admin", click "OK"
This should now bring up task scheduler, once open from the side locate; Task scheduler library > Microsoft > Windows > Windows Defender
When you have located that Choose the pre built task "windows defender schedule scan"
Right click, click "Properties"
Note that the lovely people at Microsoft have prebuilt in a scan task for us so the thing we are going to have to is set a trigger so that this task runs. To set a new Trigger click the tab "Triggers" then click "New"
Now in Triggers set the scope on when you want the scan to run and make sure "enabled" is ticked. Click "ok" and "Ok" again and it should close this window.
Now you should see your task is ready to rumble and the trigger is showing:
Then with a bit of luck and the magic touch if you go to windows defender you should see that the scan has happened at the disered time you set
my example below this ran without any user intervention :
Hope this helps !
Cheers,
Harry