Proper nutrition and a proper exercise routine. Consulting with a trainer and possibly a nutritionist will allow you to get the proper information for your goals and body/exercise type. Nutrition wise, you’ll probably be eating a lot of protein (skinless chicken breasts, egg whites) to help fuel the rebuilding of your muscles. Exercise wise, you should get a good workout of all your major muscle groups, likely focusing on heavier weights and less reps versus lighter weights and more reps.
I’ll get this out of the way: steroids are not effective in the least bit for long term, healthy muscular growth.
From personal experience, if you want to get ripped in a short amount of time, look around for a Kettlebell (or girya) class. It’s basically weight/strength training, the shape of the bell lets you do a different set of moves versus using a dumbbell or other free weights. These different sets of moves allow you to effectively exercise every muscle group in a workout with only one piece of equipment.