Hi, I'm Elise, a fellow user like yourself and I'd be happy to help with your issue.
Other users have had a similar issue to this, could you please try follow these steps to re-register the store app.
Could you open the powershell app as an administrator and copy in the following command and press enter
Get-AppXPackage *WindowsStore* -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
Now reboot your PC and this should allow you to use the store app again.
If this doesn’t work the next stage I would suggest is a repair upgrade, you can find steps on how to do this here: