Password Expiration 

If you do not update your password before the expiration date you might encounter issues with some of your private Microsoft Teams channel. Once you do reset your password, you will have to wait about 24-48 hours for the channels to reappear in your Teams app. The one issue is that you won't be a member of the private channels.  
You will have to request the owner of the private channel to add you back in. 
To reset your password, follow the steps in this guide.

More information 

For more information on this issue, you can check out the this Microsoft link 

For more help

For technical assistance, you may Submit a Help Ticket, or contact the Technology Support Center at 309-438-4357, or by email at SupportCenter@IllinoisState.edu.