Who told that your is not valid anymore? One way to know for sure is to check your CIC account and click on your Study Permit application. On that page it'll tell you whether your study permit is valid or not.
From what I know as soon as a person claims refugee his status changes and his study/work permit become invalid
As far as I know your status doesn't become invalid unless an officer tells you so. The officer who handled my case when I was a claimant told me that my study permit was still valid and I can use it to study. But I've also heard some people saying that their study permit was canceled, maybe it's on a case by case basis. I suggest that you call IRCC on Monday and ask them whether your study permit is still valid on their system or not. Good luck!