If the other parent is not letting you see your children, you should almost always go to Court as soon as possible to protect your parental rights through a temporary order.
Each married parent, if separate and living apart, has a full legal right to have the children in their custody, but a legal right is only worth something if you can enforce it. Unfortunately, the police will not get involved in domestic relations issues and will not make one parent allow the other to see the children. The only way you can protect your parental rights is though Court.
It is almost never a good idea to physically try to take the children from the other parent. Such an altercation will often result in call to the police, claims of domestic violence, and possibly a restraining order.
If the other parent is refusing to let you see your children, contact child custody attorney Marc P. Feldman today. I will advise you of your legal options and help you plan the best way to protect your parental rights.