it's fairly easy to do... google and 5 mins... some however need hardware unlock (take it somewhere) AND if u get an nlock code - only try it 2.. if u get it wrong a few times it disables that function
if it's a Nokia, i've got a DCT4 calc somewhere.... EDIT: are have a look yourself : http://www.mobileunlock.co.uk/
Try #*7337# CHeck it here if u wannbe sure http://www.mobile-review.com/forum2/showthread.php?t=18209
