Teams completely freezes after clicking on Contacts.

Contacts works in Teams on the web but freezes the Windows desktop client, so the account data and service are probably available; the failure is more likely in local Teams state or WebView. First update Teams and Windows, fully quit Teams from the system tray, and restart the computer. In Windows Settings, open Apps, Installed apps, Microsoft Teams, Advanced options, and select Repair. If Contacts still freezes, select Reset, understanding that you may need to sign in again. Reopen Teams and test Contacts before restoring optional add-ins or customizations. If the problem remains, uninstall Teams, restart, and install the current Microsoft client. Reproduce the freeze once, then immediately collect support files from the Teams tray menu or with Ctrl+Alt+Shift+1. Record the UTC time and client version. A Teams administrator can compare Client health and submit those logs to Microsoft Support; deleting cloud contacts should not be necessary.