You open QB, (in this case v2020), and enter the password, click on an item, such as an invoice, and the program just shuts down completely. You then try again, same results. No error codes or any other indication of why this happens.
Leave QB closed. Download, or open if you already have QuickBooks Tool Hub. You can get this by entering the name in a google search bar. Once downloaded and installed, click Program Problems and let the Tool run. It will show errors and repairs along the way. You should not have to respond to any errors it finds, as it will try to resolve them.
When complete, re-open QB to see if the program runs properly. If the Tool fails to resolve the issue, the next step would be to uninstall and re-install your version of QB. Make sure you have the license and product keys handy.