Resetting Security Code

I forgot my security code using Nokia 1100... i want to change my SIM card/mobile number... how can i reset the security code... I already research master security code using my IMEI number, i tried the MSC but didn't work... (code error) please help me to get or reset the security code... My IMEI number is 357593006548708.... the master security code which is generated in internet to reset is 0204376647.. Hope to solve it ASAP.... my phone is locked with security code when i change the sim then it demanded for code but i have forgotten it olz help me out in this situation my phone iemi # is 358378004521736 i purchased a second hand mobile from the market and i want privacy for my mobile so when i open the option of security code it will ask me for the previous code and i dont know that code because i purchased a second hand mobile thats why i dont know that code i forgot my security code .please help me in accessing it by providing master code i have a nokia 1100 with imei 355397009002339 and i forgot my security code...and i entered for a few times a wrong code...and after i found out my master code...this doesn`t works. Can anybody help me? forget security code