I can't find the word wall in Kilkreath Ruins anywhere i've done the daedric quest relating to the dungeon, I've searched everywhere (obviously not everywhere otherwise i would have found it!). Any help guys is very much appreciated.

There is no word wall within the ruins. However there's one just NE of the statue.

As Hayashi says.... However, if you've started Meridia's quest, the word wall will likely NOT activate.