Try:
Click and hold at the menu item "options" (cogwheel) and check if a hook is visible at "town names displayed". Change it if needed
Or:
Go to "documents" and the "openttd" folder, rename the "openttd.cfg" to "openttd.old". Start the game and you will get a new openttd.cfg file with standard settings.
Enjoy it.
Note: topics were merged because same questions