The outlook of my Ubuntu 16.04 menu changed completely and unexpectedly after a reboot.
It used to have a side-menu of items on the left, with instant access to search bar (top icon of that sidebar): Menu outlook before reboot \
Now it disappeared and is subbed by that tiny "Activities" option on top left, and simply a different top menu bar: Menu outlook after reboot \
What might've happened and how do I bring the original outlook back?
To me it looks like the "before reboot" desktop is Unity, and the "after reboot" is some kind of Gnome.
Try to choose "Unity" at the login screen.