My children are currently being cared for by my parents. I went into a long term (4 months) treatment facility in July 2009 and my parents took the boys in with the understanding that it was a temporary situation while I got well and back on my feet. It was verbally agreed to that when the boys finished school and I had a secure/safe/ stable home ready for them, they would come back home to me. All is in place and I am trying to make arrangements to get them back and they are refusing to return them to me. What can I do? Nothing ever went through any legal channels.

Which state?

If there is no court order in place or guardianship issues then you go there and take them. If they keep them or try to hide them it could be kidnapping.

They may have gotten court orders while you were in treatment. They would need to have legal guardianship to register them for school, or approve medical treatment.

But, if they did not get legal guardianship then just go get them. Either pick them up after school or just drop by the house without warning. If they refuse to let you in or give you the kids, then call the police.

Surely your parents are giving you some sort of a reason for not turning them over to you. They may feel it is in the children's best interest to stay with them. If the parents won't give them up and you do call the police expect all get out to break loose that may result in a court battle.