Will there be damage inside the iPhone when it is hit by something? My iPhone got hit and punched?

May be there could be damage inside your iPhone because as you said iPhone got hit and punched.so better go to repair shop where you can find technicians who can diagnose your iPhone and if there is any damage inside they will fix it. I had been to one of the repairing shop they gave excellent service to my iPhone which was stuck in between now after the service its working perfectly so I suggest you to visit this repair centre goo.gl/oPOQ9V