If your iPhone 4 is having problems, you might want to try a factory reset. This will erase all of your data and settings and start your phone from scratch. Here’s how to do it without a passcode.

  1. Open the Settings app on your iPhone 4.
  2. Tap General, and then tap Reset.
  3. Enter your passcode if you have one, or click Erase All Content and Settings to reset your phone without it. ..