You are able to do a “soft reset” on most phones by simply removing the battery from the phone for a few seconds. A “soft reset” will generally restore your phones systems to the original factory settings. This is useful when your phone has “froze” up or developed other “gulitches”. It can sometimes be a “cure all” for anything that has gone wrong with your phone. If your phone is acting up, remove the battery. That will probably fix the problem. The iPhone has an enclosed battery so you can not remove the battery on an iPhone to do a “soft reset”.
To do a “soft reset” on an iPhone, hold down the “home menu” button and the “power” button, both at the same time, for aprroximately 10 seconds. That will power cycle the phone off and back on and reset all of the settings to the original factory settings.
Here is a short instructional video: