A hard reset may help with a blank or frozen screen, apps crashing or freezing, keypad/touchscreen problems, can't hear, device making noises, can't make or receive calls, and device won't sync.
Performing this procedure removes all data including downloaded apps, email accounts, media files, and app data. Only perform a security wipe if absolutely necessary. Prior to wiping the handheld, ensure there is a recent backup of the data. Refer to one of the following for assistance: