How can I get enough protein to gain muscle on a vegetarian diet?

If you're a vegetarian but not vegan, most dairy products have a lot of protein. Egg whites are loaded with protein, as are beans. Getting enough protein is actually fairly easy, it sounds like you're just not getting enough energy. A creatine supplement may be helpful, but I suggest if you're going to maintain a vegetarian diet, add a little more variety so that you don't feel so drained. Also, if building muscle mass is the main objective, make sure you're keeping with the anaerobic exercises. Creatine phosphate stores will help with endurance exercises.