I'm doing 100 pushups everyday and now I'm afraid whether this will cause damage to the shoulder joints? Will this help me to gain Chest muscles?
You are seeking two answers here:
Your muscles till get used to a certain load and movement pattern after a while (4-6 weeks) based upon the neuromuscular adaptation principle. So, you have to continue to challenge your muscles whether your goal is to improve muscular endurance or increasing muscle size. And of course, proper nutrition is vital for either goal.
Hope this answer is helpful!