There is a misconception that, in circumstances of divorce and custody battles, grandparents have no rights to visit and/or be a part of the lives of their grandchildren. Some of the laws regarding this issue are set by individual states, but you may be surprised to know that, if you legally petition family court, you may well gain the right to be a real part of the lives of your granchildren.
More and more, the courts are becoming aware that grandparents can play a vital role in the nurturing and care of their grandchildren. That's why books have recently been written on the subject and some lawyers have begun to specialize in this field. You need to find a lawyer or a law firm that is dedicated to securing grandparents' rights.
It will help you a great deal if, before visitation rights were taken from you, you played an active part in your grandchildren's lives. Judges are more likely to grant visitation if you are seen to have "standing," and if you have had an ongoing, consistent, and loving relationship with the children.
Below are some links that may help. More can be found if you do a simple search for "grandparent rights." Good luck in finding a dedicated and understanding lawyer near you.
Custody cases and rights are a very touchy issue. I know that only a lawyer can guide you in the right direction. However, without a court order she holds all of the cards. You may find that you have to go to court to be able to obtain visitation rights.
I am also a grandmother and a social worker as well as a teacher. I have seen this scenario way too many times. Social service may be able to help you out if the child has just been placed in temporary guardianship and if the process went through them to begin with. However, don't expect anyone to step out of the box for you, because the rights fall to the child's parents and court appointed guardian.
I am sorry for the bad news. Please seek legal assistance if you need additional support. Good luck!