While I deeply understand PARANOIA!!!!!!! and writing style UNHAPPINESS (I have hated my writing style for over 4 years, you understand) there is only one thing to do to solve this problem.
Write more.

There are exercises you can do to try and break this -- such as writing what you're bad at, writing what you are unfamiliar with, writing without using the letter e, imitating a style, writing from the end backwards, blah blah etc etc.

But in the end it's a hard process, difficult and requires a lot of shitty writing. There is no, sadly, cure all of changing writing or making it "better." And in the end, even if you do make it "better" you could still hate it. I've written things people thought were "brillaint" and "awesome" and had solved what I hated about my writing (lack of plot and so forth) but when I read it, the piece felt lifeles and shitty.

So in the end, there is no easy answer or satisfaction to a writely distress. Just more pain |D
Yeah, that's pretty much what I'm doing. Trying to force myself back into the habit. Maybe I should look up more prompts or challenges, that might help.

sob pain.
I suggest looking for writing exercises. Prompts and challenges (as I see on LJ) are okay, but if you're in a real funk you need something awful. Or, well, whenever I am that way, I need something to jump the groove. Something to make me uncomfortable enough that no matter what I write I am still kind of ajksdbjkasd over, idk.

Or something that you can easily grab onto, but either way. Writing is pain |D
Something uncomfortable? That might work. I've never really tried anything in that direction, but my writing generally takes a rather morbid view. Still... it's something to look into.
Well, like. I spent forever trying to write a sestina (it's a poetic form) and it sucked. But the attempts to write a sestian gave some of my most fruitful writing efforts. Even though it was painful and frustrating and AHHHHHHHHH I NEVER WRITE IN FORMAT.
But that doesn't tell me what constructive critical steps I must take in order to improve on my drastically failing writing style that I seem to have adapted!!
It isn't! I just saw it in a different light--more specifically, the light filtering through bleary eyes at three in the morning.