I accidentally clicked the check box to complete a task that is still outstanding.
How can I raise it from the dead and return the task to its queue?
In order to un-complete a task, enter the project it was originally in, then click on the "Get Completed tasks" link at the very bottom of your task list and you'll see all completed tasks with checked-off boxes next to them. Simply click on the box to un-check it which will bring it back up on the active list.
Completed tasks are stored there forever unless you use the "Delete completed" link in which case the only way of retrieving any task would be through a backup. To see how backups work, please take a look at this video: http://www.youtube.com/watch?v=U96Nco_but4
Thanks Dave. I was looking in the general 'Completed Tasks' list and did not even realize there was another way to view the completed tasks.
Is there any thought to adding this function to the general 'Completed Tasks' screen as well?
The "# Completed" view in the upper-right corner is just a history of all completions you've performed on your account. Unlike the "Get completed tasks" list which actually stores completed tasks, the history in the corner lists even every completion event of recurring tasks, therefore we can't enable un-completing tasks from there as this is just a log of past events and not directly a storage of tasks.
Also - even if you would use the "Delete completed" link at the bottom, it will not clear the completion history in the upper-right corner. Still, we will of course consider clarifying the differences between these two features in our documentation.