Reformatting your phone? Here you go...
Normal reset: *#7780#
Deep reset: *#7370#
When you typed in the above key strokes, it will ask you for a confirmation security code. If you didn't change the code, the default will be 12345.
There is also another way to reformat your phone without using the keypad. First turn phone off, press and hold the green (talk) key on the left + number 3 on the keypad + the * key, and then turn the phone back on. The phone will start the formatting process without confirmation.