Hey guys, been a while,
I have a friend I've known her a very VERY long time
Anyway, she's going through some horrible boygirl stuff at the moment, the person she really wants doesn't want her.. so she's suffering the old heartbreak hotel and feeling like she can't live without this person..

Any tips on how I could put a smile on her face again

Aside from being a friend and reassuring her that I'm here to help
I mean it's a bit weird just saying OK hope you feel better soon you know where to find me...
And its not like you can just say hey it will all be OK in a few seconds when clearly she's heartbroken and feeling utterly emotionally destitute...

I was keen on her myself for a long time, but as time has passed, I've come to realise that the friendship is worth more than anything more could be at this point.
So I also don't want to give the wrong impression that I myself am interested in anything more than what the friendship already offers...

Sounds like you are putting your own feelings before that of your friends. If you are really interested in helping your friend don't acknowledge anything to do with the situation. Every time you tell her "aw" it will be OK it increases her reliance on you and perpetuates the heart break. Go by a cheap fishing pole and take a blanket to the water.