The pointing marker over the characters which is pointing towards the quest is gone..

What have I pressed, and how do I get it back?

Zeezar

You might have dragged it off screen by accident... look in your characters layout-cache.txt file located in:
%wowroot% \ WTF \ Account \ %username% \ Nostalrius Begins PvE \ %charactername% \

You should see something like this:

Frame: TomTomCrazyArrow
FrameLevel: 1
X: 356
Y: -606

Zero out those values and your arrow should appear in the middle of your screen.

Also check your !Questie.lua file located here:
%wowroot% \ WTF \ Account \ %username% \ SavedVariables \

Make sure the ["ArrowEnabled"] value is set to true

THANKS IT WORKS.....

There should probably be a slash command for this in the future (same for the tracker position).
Could also be added to the Wiki for this repository.

It's on my To Do list actually. :)

Added a code fix to prevent dragging arrow off screen in v2.3