Connections are missing

User's connection list is missing. This either mean that the Name column is missing or the Navigation pane as a whole is missing.

Solutions

The Navigation pane is visible but the list of connections is missing

Right-click where the Column name is supposed to be displayed and click on Column Chooser.

KB2019

From there, scroll down the list and double click on "Name"
KB2021

The whole Navigation pane is missing

Go to the Window tab and use Reset Layout.

KB2020