Hi, I am A. Stevens here to help with your question!
The next thing to do is a factory reset of the phone
This will erase all the data on the phone though
Hopefully you have a backup, or are syncing with your google account?
Fully charge your phone.Press and hold the Volume Up, Home and Power keys, until the Samsung logo appears.Scroll down using Volume Down and choose Wipe Data/Factory Reset, by pressing the Power Key.Scroll down (using the Volume Down key) and choose Yes – delete all user data and confirm with Power Key.Wait for the phone to reboot.