First, I presume it is a verizon phone.
1) Turn on your phone
2) Press #907*9#0
3 unlock code should be defaulted to
222222 or 000000
4) Select # 1 on the key pad for the phone # option
5) Enter the 10 digit phone number by by your cell provider
6) Save
7 enter the mobile ID number also known as MSID given to you by your provider - should be the same as #5 from above
Save
9) End to restart.

Hope this helps