Hi, I am A. Stevens here to help with your question!
You are going to have to perform a hard factory restore on the device.
If you were syncing with google before, you should be able to restore your data.
But the factory restore will erase all data on your device.
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.