Bull!! Either that principal is incompetent or s/he is lying to you. Your child’s records are OFFICIAL documents and are not private property. If you were to sue the school for educational malpractice, those documents would be needed – that’s why the teachers do not keep them.
Send a certified letter return receipt requested demanding release of the documents as provided under federal law (the specific statutes are located in this club forum in earlier messages). Send a certified copy to the local superintendent of schools and a copy to the state’s education commissioner. Show both cc’s on the demand letter along with titles. Put in a deadline of 2 weeks to produce the documents or to give you a reason why they are not being produced.