Where were you saving them? F27 would not have deleted or overwritten them.

What OS? Really, it makes a difference.

Morris Bobrow,

Are you still using Mac OS version 10.14.4 Mojave?

Are you talking about the Finale 26 app, or the Finale .musx files that you have created ?

(During the installation of Finale 27, you had a choice to remove Finale 26 or not).

you had a choice to remove Finale 26 or not

When you install 27 "the remove 26 screen", which is one of the prompt screens, goes by pretty fast. And, if you aren't reading them closely it is easy to miss it. The default is to remove 26. However, like said above even if you do miss it and the install of 27 does remove 26, all the 26 files you created are left alone. They will still be wherever you filed and stored them.

If for some reason they are not there, it is unlikely that 27 deleted them.