Why don't you post your current diet and the bros here can critique it. In order to grow, you have to eat more than your maintenance level for calorie intake. Your maintenance level is the number of calories you must eat a day to maintain your current weight. The best way to determine this is to keep a food journal. Once you know what your maintenance level is, you increase your consumption a bit, and see whether you are gaining additional lean muscle mass without too much fat, then adjust accordingly. As part of your diet, it is imperitive that you consume 1.5 to 2 times your body weight in grams of protein. You also want to include supplements like L-Glutamine, multi-vitamins and minerals.
Now here is the interesting part and it will be useful if you post your training routine. Many people don't grow because they overtrain. I see guys in the gym doing like 5 sets of five different exercises for each body part, twice a week. And while they look pretty fit, they are not growing. It is because you don't grow in the gym. You grow between workouts and these bros are overtraining. For a couple of months try hitting each body part once a week, using compound exercises. And lift heavy,,,,in the 4-6 rep range. Your chest/tri day might look like this:
Flat bench: 5 sets of 5 reps, don't pyramid, but use the heaviest weight you can use to get all reps.
Incline DB: 3 sets of 6 reps.
Weighte Dips or Decline: 3 sets
Skullcrushers: 3 sets of 6.
And that's it. You should be done in 45 minutes, but definately under an hour.
On back/bi day do: Weighted pull ups, deadlifts, rows, straight bar curl, db curl
Legs/shoulders: BB military press, DB side raises, Squats, hack squats, Stiff leg deadlifts or goodmornings, calfs.
Go heavy. Fuck the idea of going for 12 reps,,,,12 reps might give you a good pump, but it won't grow muscles.
Now I am sure there are going to be some that disagree with this form of training, but it has worked for me. I went years overtraining and seeing marginal results. But I really started to grow when I cut back on the volume of my training and started with heavy weights.