Resetting iPhone

If you have your Snapchat login details at hand, you can easily reset your iPhone and then reinstall Snapchat and then log in to your Snapchat account again!

(making a backup is recommended, Settings > Profile > iCloud > iCloud Back-Up > Backup this iPhone has to be enabled, Back up now. now you should be good to go)

But if you're trying to work around a snapchat IP ban. it won't help. if thats the case try to use a different device for it

No, not if Snapchat has banned you....because they also ban your device. You might be able to set up a new Snapchat account on a different phone.