Do you have the .tax2018 file? When you start a brand new 2019 return it doesn't find it to transfer? It should let you browse to where it is.
Here's an idea. Do you still have 2018 installed? Try opening 2018 program and see if you can get your 2018 return to show up in it. Go to FILE - OPEN. Then save it again with a name and place you can find. Go to File - Save As.
