You need to hire an attorney to help with the probate of your grandfather's estate -- I'm assuming, here, that he named you as executor as well as the heir.  One place that you can find a lawyer is our website, http://attorneypages.comHow long it will take and how much will come out of the estate will depend on a number of things.  There will be taxes that have to be paid.  The estate can be settled much more quickly if nobody contests the will.Having a will declared invalid is difficult.  Your grandfather's son who's been gone for 40 years probably knows nothing that would invalidate the will.  Your brother might be a different story, though, if you used undue influence over your grandfather to remove him, but that can be hard to prove.  There are other reasons for invalidating the will that might be possible, depending on other facts of the case.