check warranty with serial number

Hi Niloofar，

Welcome to Microsoft Community.

The easiest way to find the warranty type for your device and the coverage dates is in the Surface app: 

1. Select Start, enter surface in the search bar , then select the app from the list of results.  **Note:**If you don't see the Surface app in the search results you might need to download the Surface app from the Microsoft Store.
2. Expand Warranty & services.

You can also go to account.microsoft.com/devices and select a device to see its warranty. If your device isn't listed, select Register device to add it to your account. You'll see the coverage dates after you do this.  **Note:**If your Surface is a business device (owned by an organization), see Surface service options for Business and Education.

1. Sign in to Microsoft account | Devices with your account.
2. Locate the device that you want to check the warranty on, then select Info & support.
3. In Device coverage, you'll see what kind of warranty coverage your device has and how much time is left.

More information at Check your Microsoft warranty and create service orders - Microsoft Support

I hope this helps. If there is anything not clear, please do not hesitate to let me know.

Your Sincerely

Hahn. W - MSFT | Microsoft Community Support Specialist