HOW TO FIND LOST OR STOLEN IPHONE

I lost my iphone at school. I'm not sure if i lost it or if it was stolen.
i don't have a sim card in it and find my iphone isn't installed or used

IS THERE ANY OTHER Way I CAN LOCATE MY PHONE BACK

Please! I Really Really NEED IT

Depends on your carrier. Some can use network location as long as the phone is still powered on. If it was stolen, chances are the person who stole it knows to keep it powered off. If that's the case, your chances of recovering it are slim to none. I'm not an Apple guru, so there may be something they can do with iCloud if you contact Apple directly. If you have the original box, you'll need the ESN or IMEI when contacting Apple. Hopefully, this will get you going in the right direction. Sorry for the headache and good luck.