First you write your lawyer a brief letter requesting a refund and an accounting of any services and expenses he believes he deserves to be paid for. If he does not respond, or his response is not satisfactory to you, the Nevada Bar offers a fee dispute resolution service at this link: http://www.nvbar.org/feedispute
Your letter might read something like this:
Dear (former lawyer):
As you are aware, I have retained another attorney to represent me in the matter for which you were relieved. I request a refund of the fees I have paid to you. According to my records, I have paid to your office a total of ($xx.xx).
If you believe you are entitled to retain any portion, or all of that amount, please promptly supply me:
(1) An accounting of all services performed and expenses incurred on my behalf, listing the dates the services were performed, description of the services, the person who performed them, the value of the services, and the amount and manner of calculation of any expense; and
(2) A refund of any portion of the fee you agree was not earned by you.
Thank you for your anticipated courtesy and professionalism.