Yes-you are entitled to a copy of the will.
If someone has possession of the document-it must be filed with the court.
You should hire an attorney to force the person holding the will to comply with this requirement.
However-after three years -it is doubtful if your dad had any assets just in his name and you may have waited too long to try to prove "foul play" in someone taking advantage of your dad in his last few months of life.
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.
You could check with an attorney in the relevant state if there is a court proceeding to compel production of a Will. In NY, we have a proceeding under SCPA Section 1401, so you might see if there is a similar proceeding available. In addition, concealing a Will can be a very serious thing. Again, in NY, unlawfully concealing a Will can be a felony.
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I agree with the prior responses. How do you know that your father had a Will? If he did, it may have been filed with the probate court in the county where he resided. If he did not have a Will, the state intestate code would apply. Not sure if that would be Nevada or not, because your facts do not state where your dad lived. You have a complicated set of facts with many possible heirs or non-heirs. (Most states do not recognize step-siblings as heirs.) You have also waited a long time to do anything, which could definitely affect your rights. One thing you might try before going any further, is to check the property records for your father's home. That may help you understand what has transpired. If the house is titled in your dad's name alone, then probate would be necessary to take care of it. I am not sure why you have waited so long, but in that case, you should hire an attorney and file to open an estate, as soon as possible.
If you determine that the property was jointly owned, or there was a deed leaving it to someone else, then you need to meet with an attorney to determine if there is anything left you can do. In that case, setting aside the deed may be difficult, or impossible, if the statute of limitations has run.
*** LEGAL DISCLAIMER I am licensed to practice law in the State of Michigan and have offices in Wayne and Ingham Counties. My practice is focused in the areas of estate planning and probate administration. I am ethically required to state that the above answer does not create an attorney/client relationship. These responses should be considered general legal education and are intended to provide general information about the question asked. Frequently, the question does not include important facts that, if known, could significantly change the answer. Information provided on this site should not be used as a substitute for competent legal advice from a licensed attorney that practices in your state. The law changes frequently and varies from state to state. If I refer to your state's laws, you should not rely on what I say; I just did a quick Internet search and found something that looked relevant that I hoped you would find helpful. You should verify and confirm any information provided with an attorney licensed in your state.