App Store no longer opens or responds to clicking--just a "busy" rotating multicolor circle appears and remains. How can I get App Store to respond as it normally would?

App Store will no longer respond to any input on my MacBook Pro. It was last working prior to updating to Catalina version 10.15.2 recently. Don't recall if the problem started just prior to or after the new OS install. Have tried some proposed solutions found in online searches involving deletion of cache files and .plist files without solving the problem. Reinstalled OS after chat with Apple tech, but still no App Store response. Ideas, anyone?