Welcome @TPUL to the Instructure Community!

You mention logging in via Microsoft, which sounds to me like your Canvas instance uses a single sign-on system. That's what my instance does, and that also means that our users cannot use Canvas's forgot password link. We have to go through our single sign-on system to reset or recover lost passwords. My guess is that your returned student's single sign-on needs to be reenabled, which is a task for your local IT team. It would be great if their vigilance extended to the Canvas Question Forum, alas it does not.

I’m going to mark this reply as a solution. I realize it does not solve your problem, but it might help others in a similar situation.