Prevent Freezes and Crashes
The best way to deal with a freeze or crash is to prevent it from happening. Here are some things you can do to minimize the frequency of these unwelcome events.
Update the iPhone
Keep the operating system software on the iPhone up-to-date. Updates fix bugs and add new features. An update may even cure an otherwise unfixable freeze or crash. Here's how to check for and install an update:
Attach your iPhone to your computer, access the iPhone's Summary tab, and then click the Check for Update button.
If a check reveals that an update exists, the Check for Update button changes to Update and a dialog informs you that "a new iPhone software version is available."
From this dialog, your fastest route to installing the update ...