Open Windows Terminal or Command Prompt as Admin. Type the following command and press Enter:
Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
This command will attempt to repair the Windows Store.
If the above step doesn't work, you can try to reinstall the Windows Store using PowerShell. Open PowerShell as an administrator and run the following command:
Get-AppxPackage -allusers Microsoft.WindowsStore | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}