Before you give up on your muscle building attempts - Give these 6 tips a try first
1. You avoid carbs
Just because protein is key to build muscle does not mean you have to mainly eat just protein. Carbs also help your muscles get bigger by giving you the energy you need to workout and build muscle and when you don't eat enough carbs then your body will actually burn off your own muscle mass for energy causing you to lose muscle instead of constantly building muscle.
2. You're Not getting stronger
To build muscle fast you need to get stronger each time you workout and not weaker so doing the same number of sets, reps and same amount of weight every workout is not going to make you stronger nor will it help you gain more muscle so...
If you can't gain muscle then the first thing you need to do is make sure that you are getting stronger or at least attempting to get stronger every workout you do by using heavier weights, doing more reps and or sets.
Think about this way: you cannot get stronger and build more muscle by getting weaker.
3. You're getting weaker by not resting
If you are trying to get stronger each time you workout but you are unable to lift more weight, do more reps and or sets then you need to rest longer to give your muscles a chance to grow back bigger and stronger to allow you to lift more weight, do more reps and or sets.
4. You make isolation exercises a priority
To build muscle fast you need to do more compound exercises that work on more than 1 muscle at a time like squats, power cleans, dips and bench presses.
Isolation exercises only work one muscle group a time and are really only good for getting a "pump" and they really don't contribute to you building much bigger muscles like compound exercises do.
In compound exercises you usually use heavier weights that allow you to do less than 10 reps at a time which is ideal for building muscle mass quickly.
For example: you can build not only a much bigger chest doing dips but you'll also get bigger arms and shoulders as well but if you keep making isolation exercises like chest flyes a priority in your muscle building workouts then you'll only build a slightly bigger chest.
5. You're not eating enough protein and drinking water
Your muscle is made up of mainly protein and water so make sure you are eating at least 1 gram of protein for each pound you weigh and 1 ounce of water for every pound you weigh so...
A 200 pound person trying to gain muscle needs to eat 200 grams of protein and drink 100 ounces of water daily to consistently gain muscle mass.
If you make protein at least 30% of your total caloric diet then you should be getting enough protein in your diet to build muscle.
6. You are not using the right form
Make sure that you are doing your muscle building exercises correctly when you workout and also make sure that the amount of weight you are using is not real heavy or very light. Using bad form will only lead to injury and not muscle gains and lifting heavy weights may be impressive but remember: you need to work on your muscle instead of working on your ego.