The subject says all, nearly !
After thinking, I go to the Dock Preferences pane, discovers the PopupMenu is off, set it on.
The MenuItem comes back to disappears some minutes later.
I powered Off the MacBook, reboot in the repair partition, run Disk Utilities and reboot: it is back now, will all my Recents.
A search on Google let me know this happens to others too. Now you know what to do if this happens to you.
As usual, I do not know what happened.