You need the file ending in .tax2018 to open in the program. Can you find that one or have a backup? There should also be a file starting with a ~ Tilde sign and ending in .tax2018. Maybe you can find that one.
Did you get the program installed again ok? After you get the program installed the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW TAX RETURN)
Then go to FILE -Open and find your return.
