I have forgotten my lockcode. I have a nokia 5500 D phone and I have a setting of the lockcode if the sim card is changed can any one help me? and what is the master code?

it depends if you have changed it from the manufactures defult normally its in ur handbook or nokias are normally 0's eg. 0000 or 000000, 00000000 if not u will have to look on google for a hack or if you can get on the phone back up everything and master reset it