Hello and thank you for your question today. My name is Jason. I look forward to helping you today.
You will have to restore the iPhone
to a base firmware install, which will erase everything on the iPhone, but you can later restore the contents of the iPhone to a backup that you have on the computer (the same computer you used in the past to sync the phone with):
- Press and hold the top power button until the iPhone turns off
- Connect the iPhone to the computer that you have been using the phone and iTunes with
- Hold down the HOME button on the front while pressing the Power button (continue holding the home button)
- Continue to hold the HOME button until you see the "Connected to iTunes" message
- In the Summary tab, click Restore and follow the prompts. (THIS WILL ERASE everything on the iPhone and make it just as it was when you first purchased the phone).
- Once that is complete, right click the iPhone listing in the left panel of the iTunes window
- Choose "Restore from Backup"
- Choose a backup date and restore.
Now your iPhone will be back up and have all the restored information from your last sync.
If this does not help, then you may have to considering bringing it into a repair shop or replacing it.
If you have any questions, I am available to continue.