Fall Creators Update Corrupted Store

Try one of these 2 tutorials :
How to Re-register the Store in Windows 10

How to Reinstall and Re-register All Built-in Windows Apps in Windows 10


*** Adding :
There are 2 more suggestions/recommendations for you.....

1. Create another user account with exactly the same privileges as the one you are now using > logon to it and see if the Store and the apps work correctly.
If it works, then your original account is corrupted. Backup files you want to keep and delete the old account.

2 Repair Install.
I hope you would not have to come to that.
However, if none of the above works for you, you might need to do a Repair Install of Windows 10.