If you have suffered from any virus attack and the default Windows task manger has been disabled then in such a situation it becomes very difficult for an average user to over come the situation. Though the best way to get rid from the above problem that you should use a good anti virus program and keep it updated with the latest virus databases. Or you can also try the below solution to easily fix the problems regarding Task Manager or registry editing disabled or the folder option settings missing in explorer.
But in case if you want any alternative for the task manager system then you can try DTaskManager, obviously, is a Task-Manager, but specifically engineered to give additional functionalities that the Windows bundled TaskManager (and other third party products) do not have like you can terminate any application or process using forced termination, you can also temporarily deactivate or reactivate any process.
With this tool you can also terminate multiple processes at once from a single selection. In all it is a good tool to try even if you don’t have any virus attack or even if Task Manager is working.