Hello my name is Daniel.
Your contact info is backed up to Google, all your info which is saved to SD card is also safe. Do you have any other info that is not backed up or that you absolutely cannot lose?
Ok here's what you do:
1. Power the device off. If it's frozen, pull the battery, then place it back in the device.
2. Press and hold the Volume Up, Home and Power buttons simultaneously.
3. Follow the setup instructions on the screen
If this works and you're able to get into the phone, just click the green "Accept" button.