There are several ways to find a Last Will & Testament. In your case you should start with asking your God-Father. The second step would be to look at the Probate Court with jurisdiction where your Father was a resident. You also could go to the State Bar Association and have them run a Will Search Ad in the Bar Newspaper. You also could hire an attorney to assist you with searching for the Will. What is going to be asked, is why are you looking for it? If your Father passed 12 years ago, it is likely that any assets that your Father owned were administrated 12 years ago. Unless you have found new assets that you need to change into your name, it may not be necessary to find the Will. Also, if you cannot find the Will, and you have found assets that need to be Probated, you can file for Probate without a Will. Good Luck.
Answer Applies to: New Hampshire
The best way to find the will is to simply look for it in all his "hiding places" or in family safe or safety deposit box. If those things fail, then you may have to speak to his family attorney who he used at that time and see if the attorney kept the Will in his/her safe or elsewhere or if that fails, whether he/she has a copy of the Will in their file or computer memory. A Will can still be proved using a copy together with two witnesses who watched it be executed or even the attorney who prepared it. Good luck.
Answer Applies to: New York