You can press the menu key and when it is asking for the security code hopefully you have not change the security then enter the default code 000000, if you have changed the code then take the mobile to a service center close to you to have them reset the phone.
Answers & Comments
You can press the menu key and when it is asking for the security code hopefully you have not change the security then enter the default code 000000, if you have changed the code then take the mobile to a service center close to you to have them reset the phone.