Why do sometimes i feel like crying?

Sometimes when im alone i just feel like crying. i feel like my lifes not important or anything and i just wish someone like umm edward cullen or whatever will just come and i keep waiting for something like that to happen. i feel like i am not important but if i become noticed i will be. i have a lot of friends and i had a good childhood and stuff. im very young, in my young teens. idk just someone help or something