How to Fix the Calculator App Not Working in Windows

 Re-register Windows apps via PowerShell

Since the calculator is a default application in Windows, you can possibly repair it by re-registering these Windows apps.

1. Press the Windows + S keys on your keyboard to bring up the search tool, then look for “PowerShell.”
2. Right-click on “Windows PowerShell” from the search results, then choose “Run as administrator.”
3. If prompted, click Yes to allow PowerShell to make changes on your device.
4. Once the application is open, copy and paste the following script into it, then press the Enter key on your keyboard to execute it: Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)AppXManifest.xml”}
5. After the process of re-registering the Windows 10 apps has finished, try using the Calculator app again.