Estates and Wills etc?

My father died in 1981, about three months before he was supposed to. (He choked on a tube in his throat). Well, needless to say he never mentioned the house in his will but did ration is other assests, (money, etc). It is a long story, but we all have just been told, since we need to sell the house, that because my father did not mention the house in his will that it is not ours. I know my father probably thought it automatically went to us and did not know he had to include this.
Does anyone have any answers?

My sister wants to sell the house because the neighborhood is dangerous.
But we really don't understand why my father would have mentioned it in his will.
I am supposed to sign and notarize a document giving authority of ownership to some administrator. My kids think I should look more into it it before I get it notarized. I don't know who to ask who will not charge a large fee. It has to be back in new York by the 20th of March. I live in California.

EDIT: If you are over 60 or your income is below a certain level you can probably get help at the civil legal aid office in your city. Another option would be to contact and area law school as these tend to have student-run clinics to handle civil law matters (don't be concerned they are all supervised by bar-admitted professors). They can help you look at the details of how the rest of the estate was divided and the specifics of the document you have been asked to sign.

Hmm, who told you after 26 years that you have to sell the house? This will of course depend on where this is occurring but typically this property would just be assumed to be shared as the rest of the estate. For example, if dad had 3 children and left 1/3 of his cash, stocks, etc to each child then each child would be presumed to have a 1/3 share in the house. If you were child 1 and child 2 says you must sell the house her actual claim would be for her 1/3 value in the house. This value would be based on the value of the home in 1981.