A Rare problem found in Windows where Task Manager greyed out and could not enable it even in Administrator mode.
How to fix greyed out Task manager problem?
Enabling Task manager
Go to Start > Run and type ‘regedit’
You will then have a menu on the left-hand side of the menu. Select HKEY_CURRENT_USER > SOFTWARE > MICROSOFT > WINDOWS > POLICIES > SYSTEM
From there you should have the option to enable Task Manager by double-clicking on DisableTaskMgr and changing the ‘Value Data’ field from 1 to 0.
You should now be able to see Task Manager by right-clicking on your Task Bar