I would recommend backing up your phone, resetting and then reactivating it on the network. Steps are below to complete these operations;
Back upyour IPhone if possible.
Tap Restore from iCloud Backup.
Enter Apple ID and Password then tap Next.
If customer has a iTunes backup of a previous iPhone:
Tap Restore from iTunes Backup then tap Next..
Connect iPhone to computer that has the iTunes backup of pervious iPhone and follow onscreen instructions from iTunes.
Check out a fun infographic that teaches you how to increase storage, enhance security, improve battery life and clean your device.