How do I fix my metabolism?

So I have been obssessed with losing weight this whole entire year, I have done and tried practically everything, diet pills(I stopped) water fasts(done a few but stopped) juice fasts, eating 500 calories and less a day, I realize that its bad now, so I am wondering, am I screwed, or are their ways for me to fix the damage I have done to my body.
How do I fix my metabolism?
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