How to Reinstall Mobile OS

Where to Find Your Mobile OS
Depending on your cell phone or smartphone's make and model, you will have a desktop program available to carry out installations or updates. These programs will help you download or re-download your mobile phone's operating system. Examples include the BlackBerry Desktop Manager for BlackBerry, iTunes for Apple iPhones and PC Companion for Sony Ericsson. Each program is different, but most will allow automatic, easy-to-follow installations or upgrades of your phone's OS.
Installation Procedure
Load the installation wizard that came with your phone and download the mobile operating system install file for your phone to your computer. Depending on your phone, you may download the OS directly or through the phone's compatible installation wizard. Connect your phone to your computer using its USB cable. Follow the wizard, complete the installation and allow your device to reboot. This will reinstall or upgrade the operating system on your phone.
Problems
Most cell phones, in particular smartphones, are eligible for operating system reinstallations and updates, but not all. Check with your provider for information on your specific model.