Drugs ruined my body, ate away at my muscle, how long will it take...?

My entire life i've had a huge , big, round, full and perky. it's always been my trademark, it's always been my best et. went on a vacation about a month ago, and while i was there i partied a little too hard, cocaine all week barely ate a thing, i dropped so much weight. when i came home i craved that uppers feeling, so i continued to drink atleast one energy a drink since then, now my is nearly gone, it was big with muscle before, the muscle is gone. it's never in my life been this small, even thinking back to middle school. I'm guessing my body started to eat away at my muscle, and ate away at where i store most of it- my . This has upset me so much to the point i can't sleep, people and friends have noticed, I'm driving myself crazy with this, will working out really bring my back? How long would that take? Any advice would be great, thanks..