I Am 13 And My Tooth Has Fallen Out. I'm

I am 13 and my tooth has fallen out. I'm not quite sure if it was a baby or an adult but Google's really freaked me out. I'm afraid of dentists too (that and mascots, lol) but its left a lump of red squishy stuff and I don't know whether or not to put the tooth back in or leave it? Theres a tooth growing next to it at the back but I don't have enough room I my mouth. Its not a wisdom tooth because its not right at the back. My parents aren't home either. I don't know what to do?