Can you lose your parental rights if you as a parent placed the children in care of their parental grandparents?

You have full parental rights over your children until a court order says otherwise. You need to consult with a lawyer immediately and show them whatever lawsuit was filed against you. There are certain arguments that can be made to try and keep your full parental rights, but if you have effectively abandoned your children for over a year and have used any illegal substances over a period of time, you are definitely on the defense and will have to fight to keep any rights and visitation with your children. They could be trying to terminate your parental rights as well if you abandoned the children or have placed them in danger with your drug use. There are drug tests that can be done to help determine whether you have a substance abuse problem. For the sake of your children, please get clean and sober and seek legal advice.