My calendar is showing a lock icon next to the network icon and I don't get prompted for my password?

The calendar function quit working. It is showing a lock next to the network icon and it never asks me for my calendar password. When I try to create a new calendar I get to the point where you select the "Check server and mailbox" I get the message: Error during checking of server and mailbox: HTTP Client error 401: Unauthorized URL:https//outlook.office365.com/EWS/Exchange.asmx, (Code: -19). My thunderbird version is 52.1.1, my lightning version is 5.4.1.1 and my Exchange EWS version is 3.9.0 Also email is working just fine so I don't understand why it's having trouble with the calendar. Any help would be appreciated. Larry Pesek