why can‘t open App store?only a black screen is display

Follow the advise of @Luis S

For good measure >> Suggest downloading from a Trusted Developer and Respected ASC Contributor the application Malwarebytes for Mac. It is free or paid for added features. Run the Application and it should remove the malware / adware. Once done, restart computer and test.

There are no known Viruses in the wild that self replicate and affect macOS. There are Malware and Adware that does affect macOS and are often times downloaded as part of an Application from Third Party UnTrusted Site and get installed along with the Application.

There have been some similar cases, and in all of them the user had installed some form of adware.

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

Welcome and Thank you too :-))

Just for the record - had you followed the advise of @Luis S and run the Etrecheck Application - it too would have " Works " fixed the issue of Malware or Adware.