Here are a few things to try out when your iPhone freezes up on you.
The iPhone maintains many of the same issues that any computer has. This is one of the unfortunate angles of the power of the iPhone machine, which mixes diversity and complexity in a way that can be stable but is still prone to problems. Occasionally the iPhone will freeze or have a similar issue of unresponsiveness. Here are a few tips on how to deal with these iPhone situations.
On occasion, an iPhone application will freeze in the middle of processing. Usually you can get out of an awkward application moment simply by hitting the Home button. If it completely freezes and that does not work, you can press down the Home button and hold it for six seconds. This will be a force close on the frozen application.
Total Freeze Out
The entire iPhone is also prone to doing the same thing on occasion. This is often inexplicable in the specific situation, but it can stem from not being synced often enough or having too many pages of unused iPhone applications. If it does lock up on it you need to do a forced “hard" reset. You do this by pressing and holding down both the Home and the Sleep and Awake button on top of the iPhone at the same time. That will make the screen go black, then you will get the start up Apple logo when the iPhone reboots.
On occasion neither of these things will help with your frozen iPhone. This can cause a huge problem because it will seldom unfreeze on its own. Usually plugging in to power directly will not help this, but occasionally this will be enough of a jolt to get it going. The real resort here should be to plug it into your computer and sync it back with iTunes. This can be one of the main reasons to work consistently with your iPhone in conjunction with a computer instead of just trying to use iTunes and the App Store on your desktop. You can also try calling your iPhone from another phone to see if you are able to receive calls on it.