In the order of which steps I would try:

#1 REBOOT, that often fixes things, if that fails then

#2 Run 2019 Lacerte Web Setup to reinstall the latest update if that fails then

#3 Use the Force install shown at https://proconnect.intuit.com/community/help-articles/help/how-to-perform-a-force-install-of-lacerte... if that fails then 

#4 Contact Support https://proconnect.intuit.com/community/help-articles/help/how-to-contact-lacerte-for-help/00/4691