Q: I'm trying to activate my iphone that i got used. i restored it to factory settings and it says it is activated under the previous owners apple id. They are not with me nor do i know how to get a hold of them. What do i do to reactivate it?

There is nothing you can do without the previous owners intervention.

Find My iPhone Activation Lock: Removing a device from a previous owner

If you cannot contact the previous owner, then the iPhone is unusuable. There is no way past the activation lock without the Apple ID and password used to set up the lock, or the previous owner removing the device from his/her iCloud account.

If you purchased the iPhone though a service such as eBay that offers buyer protection, contact that service and file a complaint and get your money back. If you purchased the iPhone privately, then you've wasted your money.

Regards.