Who have a right in land property the owner if my uncle and auntie was already dead?

You can file a petition in probate court and ask a judge to determine the heirs.

You need a Missouri lawyer if the land is located in Missouri. Under Missouri law, if a person dies with no wife and no children, the heirs at law are the children of any child that the deceased did have. So, if your aunt and uncle's son had children, his children would be the heirs. If there were no children then, parents, brothers and sisters of the survivor of your aunt and uncle would be heirs. This is a VERY TENTATIVE ANSWER. Retain counsel at your earliest convenience and don't attempt anything without doing that.

Your summary is very confusing. The land DOES have title. Ownership can be confirmed with the county register of deeds. The question is who gets title, based on your circumstances. You do not mention whether your aunt and/or uncle had a Will or Trust. You do not mention the order of death. An "illegitimate child" is considered a legitimate child, for purposes of inheritance. There is a presumption that a child born to the wife during a marriage is the product of that marriage. You may be able to prove otherwise, but the burden of proof would be on you. In the absence of a Will, a Trust, or a deed indicating who the owner was to be upon the death of the prior owners, state law would apply. The intestate law dictates who is the "next of kin," for inheritance purposes. That might be you, or it might be you and a bunch of other people, or it might be someone else, completely, depending on the facts which are not included in your summary. You appear to be long overdue for a meeting with an attorney. I believe that is the only way you will be able to make sense of this.