I can't suddenly check the work of my team.

I had the same problem yesterday, and this worked:

Reset Teams

Go to Windows Settings > Apps > Installed apps (Windows 11) (or Settings > Apps > Apps & features on Windows 10)

• Select Teams > Advanced options > Terminate > Repair > Reset

Note: Reset clears local app data but does not delete your cloud messages.

Expected result: You’ll be signed out; after signing in again, Chat should work.

Hi 이아현,

Welcome to Microsoft Q&A.

This usually points to the Teams desktop app not fully initializing chat due to cached sign‑in information or local app state issues. Since Teams works correctly in the browser, the account and service are likely fine, and the problem is typically local to the app on that device.

Temporary option (so you can keep working)

For now, you can continue using Teams on the web for chat while you fix the desktop app.

Steps to try on Windows (depending on what you have installed)

1) Sign out and fully quit Teams

• Profile picture > Sign out
• Right‑click the Teams icon in the system tray > Quit
• Reopen Teams and sign in again

2) Reset Teams

Go to Windows Settings > Apps > Installed apps (Windows 11) (or Settings > Apps > Apps & features on Windows 10)

• Select Teams > Advanced options > Terminate > Repair > Reset

Note: Reset clears local app data but does not delete your cloud messages.

3) Manual cache clear (deeper reset)

Only do this after quitting Teams completely.

• Press Win + R > paste: C:\Users\%username%\AppData\Local\Packages\MSTeams_8wekyb3d8bbwe
• Delete or rename the folder (or its cache‑related contents)
• Reopen Teams and sign in

if the issue persists

• Are you signing in with a work/school account or a personal Microsoft account?
• After the reset, do you notice any warning banner in Teams (for example, indicating chat is running in a reduced or limited mode)?

Please let me know if this proves useful to you, or if you would like further assistance.

I'm looking forward to your reply.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment”.   

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Follow these steps to restore chat access in the Teams desktop app:

1. Restart Teams completely
   • On Windows, go to the taskbar, right‑click the Microsoft Teams icon, and select Quit to fully close it.
   • Start Teams again and check if chats load.
2. Verify sign‑in and access
   • If a banner appears asking to Sign in, select it and complete sign‑in (including MFA if required).
   • If no window appears, right‑click the Teams icon in the system tray and select Quit, then reopen Teams and sign in again.
   • Ensure the required network/VPN (if any) is connected before opening Teams, and avoid switching networks while Teams is running.
3. Try Teams on the web
   • Since chat works in the browser, use https://teams.microsoft.com as a temporary workaround while troubleshooting the desktop app.
4. Clear the Teams cache on the device
   • Close Teams (right‑click icon in taskbar → Quit).
   • In File Explorer, open %appdata%\Microsoft\Teams and delete all contents of this folder.
   • Reopen Teams and sign in again.
5. If still blocked from chat only
   • This can be caused by account or policy issues (for example, security policies, device compliance, or risk‑based sign‑in). Contact the organization’s IT admin so they can:
     • Check if any conditional access or security policy is limiting chat.
     • Confirm the account is in good standing and not restricted.

If none of these steps resolve the issue and the banner continues to appear, IT admin support is required to review account‑related errors and network or policy requirements.

References:

• My chat messages aren't loading in Microsoft Teams
• Restore your access to Microsoft Teams
• I can't reconnect to Microsoft Teams