You can get the unlock code here mobile-unlocker.com to your mobile Nokia 5300....After that follow the following instruction...
1 - Switch on your Nokia 5300 without any sim card.
2 - Don't bother as to what is displayed on your Nokia 5300.
3 - Compose #pw+CODE+1#.
4 - The Nokia 5300 would then display the message "SIM Restriction Off" and will be unlocked!