1
Open PowerShell by right clicking its icon and select 'Run as Administrator'.
In PowerShell, run this command and press Enter:
taskkill /f /im explorer.exe; start explorer.exe
When that command completes close PowerShell and check if that resolves the problem.
2
If that does not resolve the problem, open the Settings App.
Go to Personalization - Colors.
Toggle the 'Choose your Mode' setting a couple of times between Dark and Light Mode to test if that resolves the problem.
3
If that does not resolve the problem.
In the Settings App, go to System - Recovery.
Click the 'Reinstall Now' button in the 'Fix problems with Windows Updates' section, then wait for that process to complete.
That process should fix any corruption in Windows and it will not affect your files, settings or installed apps.