Hi Mustapha, If you've locked your phone through entering an incorrect pin number 3 times then you need a Puk code, Ring your service provider and they will give you the FREE Puk code.....
If you lock your phone again some time in the future and you're still with the same service provider you can use that same Puk code.. BUT if you want to factory reset then the link below is a short youtube video on how to rest the pattern code on your phone, The
guy shows 3 way but the 3rd way is a factory reset meaning you loose every thing in your phone
but the first two ways are worth watching. I hope this helps...... CHEERS.. https://www.youtube.com/watch?v=dmBqvh1UUD4 EASY WAYS How To Unlock Android Passwords