Hello Julie,
#1 I'd recommend going down to the bottom right corner where your Teams icon is and right click > Sign Out
#2 Restart your device and try signing back in.
#3 If this does not work I'd try clearing your Teams files cache:
https://learn.microsoft.com/en-us/microsoftteams/troubleshoot/teams-administration/clear-teams-cache
If this is helpful please accept answer.