If you no longer have your old will, you should create a new one. A will that no one can find is often worse than no will at all. Creating a new will does revoke a prior one, but it is best to expressly revoke the prior will in the new one to avoid any confusion about your intent.
I agree with Ms. Boyd and I'd also add that in this circumstance, with more than most on the line due to your situation, I would recommend having an attorney assist you with the drafting and signing of the will rather than attempting it on your own.
In the new will you should make clear that the new will is your last will and that you revoke all prior wills and codicils. A codicil is essentially an "amendment". Under your circumstances a new Will would be better.
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I agree with my colleagues that it is best to do a new Will, however, if you are still married, you can only give away your separate property interests and 1/2 community property interest in a Will. You cannot entirely disinherit your husband under Nevada law, as he will always have his 1/2 interest in any community property the two of you have. You may want to consider divorce or a legal separation if you want to truly disinherit him. Either way, you will want to do a new Will even before filing for divorce or legal separation to ensure that you dispose of as much of your community property as you can. Please feel free to schedule a consultation with my office if you have further questions.