Assuming you haven't been able to do anything yet with ProSeries TY20, i'd suggest deleting the entire installation directory (probably C:\ProWin20) and running the installer again.  

Here's the direct download link

Professional: https://ftpfp.proseries.com/pub/proseries/2020/CoreInstallerTY20.exe

Basic: https://ftpfp.proseries.com/pub/proseries/2020/BasicInstallerTY20.exe

Keep an eye on the installer - make sure it runs all the way through. When you get to the final "Successfully Installed" screen, open File Explorer, go to the install directory and look in the 32bit directory. It should have about the same number of files as your TY19 folder, including the ProTax exe.

In terms of why you got in this state in the first place... not sure at all. Can you open FileExplorer, navigate to C:\ProgramData\Intuit\ProSeries\Install\TY20\Logs, and email the files found there to proseries_engineering@intuit.com?