None of the helpers I’ve worked with have had any fixes for it
I’ve had altogether (I think) 4 years of actual psychotherapy (3 of which group therapy of $deity-knows-what school, 1 brief intervention-type CBT thingy to cope with a crisis), and in between those something like 10 years of (usually weekly) sessions with psychiatric nurses or a psychologist (not considered actual psychotherapy).
The reason was my (ongoing) depression, and I’ve always brought up the emptiness inside being at the core of my problems, and unfortunately none of the helpers I’ve worked with have had any fixes for it. The biggest focus on it I’ve had was with the (also CBT) psychologist, but even with her in the end we just had to put it (along with the cynical worldview I’ve developed from it) aside, thinking I could perhaps go on with my life despite it being in the background. That’s been the only option available, and it’s not a very good one I’m afraid.
The closest I ever came to an actual fix, I think, was a brief moment (during my time with the psychologist) when I had the idea that I could perhaps turn this emptiness into my source of motivation. Since the emptiness really has felt indestructible, it’d mean I’d have virtually never-ending reason to push forward. But that too just doesn’t work in real life like it does in TV Tropes (http://tvtropes.org/pmwiki/pmwiki.php/Main/PowerOfTheVoid).