Nokia N72 — keypad malfunctioning

dear sir,
as i installed some information in the "security" icon under "my own" folder i found my keypad to be malfunctioned and not responding. even i m not able to access my messeges and missed calls. when someone calls me he hears the phone ring on his phone but there is no ringtone or lights on my phone.
plz help me out n tell whether its a software problem or something else?
Umakant Anand