I have task list but I didn't find the checkbox (mark task complete) option in my task list.
Thanks in adavance
It is the
Completed column in a Tasks list that is displayed as the Checkbox.
hierarchytaskslist.js was not executed on the ListView.
One scenario can be you have attached JSLinks on the WebPart, this prevents execution of any JS files attached to the View definition
As seen in the screenshot below of a standard Tasks list; all Views make that Completed column work until a JSLink is set on the WebPart
Solution is to add the
hierarchytaskslist.js to the JSLinks of the WebPart
not done yet in the screenshot below
The https://365csi.nl/icsr/linkmanager/ helps with managing JSLinks
hierarchytaskslist.js with one click.