Alright here are some options,
1.Delete snapchat (if u know ur login information)
2. Delete all storage (apps, pictures,videos)
3.Press and hold on the off/on button when its on until the screen turns dark and charge it at the same time
4. Leave the battery out of the phone for a couple of minutes.
5.just update the phone, if you dont know how go to settings If u have the search button on settings Search up, Update and just continue .