When deleting tasks or messages, Cerebro only marks them as deleted and no longer shows them to users. You can restore deleted tasks and messages together with their corresponding files at any moment.

Main menu > View > Show deleted tasks.

After this option is turned on, all deleted tasks will be shown in the Navigator, and messages will be shown in the Forum. By right-clicking the deleted task or message, you can select the menu option Restore...

After restoring, you can turn off displaying deleted tasks or messages.