teams app in windows culd not sign in

Hi Qin,

Thank you for reaching out and sharing the details of your Microsoft Teams issue.

This situation usually occurs because the previous uninstallation left behind old cache data and saved sign-in information, which then conflict with the new Teams app and prevent it from connecting properly.

To get Teams working again, please follow the solutions below in order:

Solution 1: Reset the Teams app to clear old cache data

• First, right-click the Teams icon in the taskbar tray at the bottom right corner of your screen and select Quit.
• Next, open Settings, select Apps, and then choose Installed apps.
• After that, find Microsoft Teams, click the three dots beside it, and select Advanced options.
• Finally, click Repair, and if Teams still cannot sign in, return to the same page and click Reset.
• References:
  • Clear the Teams client cache - Microsoft Teams | Microsoft Learn
  • Clear the Teams cache - Microsoft Support

Solution 2: Remove old saved sign-in credentials

• To begin, open the Start menu, search for Credential Manager, and open it.
• Then, select Windows Credentials to view your saved sign-in entries.
• Afterwards, remove every entry that includes the words Teams, msteams, or Microsoft Office.
• Once this is done, restart your computer and try signing in to Teams again.

Solution 3: Perform a clean reinstallation of Teams

• If the issue still continues, go back to Settings > Apps > Installed apps and uninstall every version of Microsoft Teams shown in the list.
• Following that, restart your computer so that all remaining Teams processes are fully closed.
• Lastly, download and install the latest version of Teams directly from the official Microsoft website, then sign in with your account.
• Reference: Download Teams Desktop and Mobile Apps | Microsoft Teams

Additionally, once you have signed in successfully, please open Teams Settings, select Devices, and confirm that the correct microphone is selected so that your audio works as expected.

I hope these steps help you regain access to Teams. Please let me know if you have any questions or if there's any update after trying the above steps.