Can you try running the Windows App Store troubleshooter please? That will run a few tests, which may be able to fix it before we try other options
.
If you click Start > Settings > Update and Security > Troubleshoot and then select
Windows Store Apps from the very bottom of the list and run the troubleshooter. It'll perform some diagnostics and can usually fix things
.
If that doesn't work, please let me know and we can try the next step.