Open PowerShell as Administrator, then run this command and press Enter:
Get-AppXPackage | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
When that completes, run this command and press Enter:
Get-AppxPackage -allusers Microsoft.WindowsStore | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
Close PowerShell when that completes, restart (not shut down) your PC and check if the Store is working correctly