Definition: A hard reset is when you remove the BlackBerry's battery and all connections to any other power sources (e.g., USB cable connected to a PC or a BlackBerry charger), and then replace the battery. This severs all network connections, forces the device to reboot, and can resolve many BlackBerry software issues.
Performing a hard reset is a typical troubleshooting step to resolve BlackBerry issues. If your BlackBerry is frozen or will not allow you to perform a soft reset, you should perform a hard reset. Rebooting your BlackBerry on a regular basis may help you avoid performing hard resets.