I suspect there is no output from get-appxpackage Microsoft.UI.Xaml.2.7 -allusers as suggested by Ramesh, as there was for me. I had a similar problem with the Microsoft Store and other apps including Mail and Notepad not opening.
I managed to install the missing framework as follows:
- Go to https://www.nuget.org/packages/Microsoft.UI.Xaml/2.7.3 and click the Download package link on the right-hand side. This downloads a file named microsoft.ui.xaml.2.7.3.nupkg.
- Replace the files .nupkg extension with a .zip extension.
- Right-click the file and select Extract All... and then Extract. This creates a folder named microsoft.ui.xaml.2.7.3.
- (You may want to reboot your machine before performing this step as it may fail if certain files are in use.) Open PowerShell as Admin and type Add-AppxPackage -Path "C:\path\to\microsoft.ui.xaml.2.7.3\tools\AppX\x64\Release\Microsoft.UI.Xaml.2.7.appx" replacing *\path\to* with the location of the microsoft.ui.xaml.2.7.3 folder and \x64 with the appropriate platform (I have 64-bit Windows 11).
- Press enter.
- In PowerShell type get-appxpackage Microsoft.UI.Xaml.2.7 -allusers which should now show details of the microsoft.ui.xaml.2.7 package.
- You should now be able to install/open the Microsoft Store app.
Regards, Steve.