Webapp Version
Go to your project, then in the task section click on the "Archived elements" icon. Drag your mouse over the task you want to restore then click on the 3 small dots on the left corner of the picture. Now click on the circle to restore your task.
Now your task has been restored.
Android Version
Go to your project, then in the Tasks section click on the button with the three vertical dots at the top right of your screen.
Select "Archived Elements" to find the tasks you would like to restore.
Click on the circle to restore your task
Now your task has been restored.
iOS Version
Go to settings in the right bottom corner of your screen
Click on "Show archived elements".
Now all the archived items will appear in the Tasks section.
Dag the archived task to the left, then press Restore.
Now your task has been restored.