They have to keep, and provide, the records for usually 5-7 years, depending on the state. If you had some sort of proof or if you had known (not likely as a teenager) that it was your right at that time, you probably could have gotten your records. At this point, if it's past the 5 or 7 years since you were in there, there's likely nothing that can be done unfortunately, except to help educate people who more recently got out of a facility.