My chat history/message between 12/12/2025 and 28/08/2026 has been deleted or disappeared.

Hello @Hailey Kim,

I'm sorry to hear you're experiencing this issue. Losing access to a large portion of your chat history can certainly be frustrating.

As an independent community contributor, I don't represent Microsoft and don't have access to Microsoft's internal systems or the tools required to investigate account-specific data or restore messages. However, I can suggest a few troubleshooting steps that may help determine whether the messages are hidden, not syncing correctly, or have been affected by a policy or account-related issue.

Please check the following first:

1. Confirm you're signed in to the correct account and organization

If you have access to multiple Microsoft accounts or tenants, verify that you're currently signed in to the same account where the chats originally existed. Missing chat history can sometimes occur when Teams is connected to a different organization than expected.

2. Test Teams on another platform

Please compare the results across:

• Teams desktop app
• Teams web app (https://teams.microsoft.com)
• Teams mobile app (if available)

If the missing messages appear on one platform but not another, the issue may be related to local synchronization or cache rather than actual data loss.

3. Search for specific messages or participants

Try using the Teams search bar to search for:

• Keywords from conversations during the missing period
• Names of participants involved in those chats

Sometimes older chats are not immediately visible in the chat list but can still be found through search.

4. Clear the Teams cache

If the issue only occurs on the desktop client, clearing the Teams cache may help resolve synchronization problems.

Before doing so, completely sign out of Teams and close the application, then follow Microsoft's guidance for clearing the Teams cache and sign back in: Clear the Teams client cache - Microsoft Teams | Microsoft Learn

5. Check with your Microsoft 365 administrator

If this is a work or school account, your administrator may be able to verify whether:

• Retention policies have changed
• Messages were removed due to compliance settings
• An account migration or tenant change occurred
• There are any service-related issues affecting chat history

If you don't know who the Microsoft 365 admin is in your organization, you can find guidance here: How can I find my Microsoft 365 admin? - Microsoft Support    

6. Contact Microsoft Support

If the messages are missing across all devices and platforms, Microsoft Support or your Microsoft 365 administrator will be best positioned to investigate whether the data still exists in the service and whether recovery options are available.

(Since the thread is categorized under Business, the guidance below applies to organizational accounts. If your situation involves a personal Microsoft account, such as Outlook.com or Hotmail, please inform me so I can supply the appropriate instructions.) 

1. Find your Microsoft 365 admin: If you don't know who the global admin is in your organization, you can find guidance here: How can I find my Microsoft 365 admin? - Microsoft Support    
2. Submit a service request: The Global Administrator should create a support request with Microsoft to receive advanced technical assistance. For detailed instructions, see: Get support - Microsoft 365 admin | Microsoft Learn    

If your subscription is from a partner or reseller, contact the reseller's support provider to help open a service request on behalf of you instead.    

If you discover any solutions or have additional insights, please consider replying to this thread to help others in the community.   

I hope this helps point you in the right direction. If you still run into any trouble, please don't hesitate to let me know. I'll be happy to continue assisting and look into any additional information you can provide.