If my father left his belongings to his widow in his Will, does she have to give or leave anything me even though she is not my biological mother?

First of all, children can be disinherited; they do not have an automatic right to inherit from a parent (that having been said, in some states the Will must contain certain specific language in order to disinherit a child). Accordingly, as your father's sole beneficiary, his wife will receive all assets that are passed in his Will. Any assets not part of the probate estate, such as life insurance proceeds, will pass to the named beneficiary. Additionally, jointly held property with rights of suvivorship, will pass to the other joint owner.

When your stepmother passes, she can bequeath (i.e. gift) her assets as she chooses in her Will. If she dies without a Will, her biological and/or adopted children (and spouse, if any) will inherit her estate. Bottom line, you have no rights to her estate.