As stated, I feel a litle silly for having to ask this over the forums but…
While using the script editor my hand slipped and I pressed a key (not sure which), now all my highlights are gone and my script has no font or colour anymore. May as well be scripting in notepad.
Anyone know what I pressed?
Thanks.
After spending 10 minutes in the ‘View’ tab, turns out the answer was in the ‘Language’ tab. =/
Yeah so basically i think i pressed F12 which changed the application to HTML mode. Once i clicked JavaScript it went straight back into highlighted mode.
Thanks anyway all.
Panic over 
I do stuff like that a lot. It’s a world of adventure and discovery.