If you reinstall the program from scratch then all the updates for that program need to be installed as well. Before you can open up the 2018 tax file the program must be updated and if you had a state return in that tax file the state programming also needs to be installed and updated. To do this you need to start a fake return and enter in just enough information so that the state program can be installed. Once the federal and state are installed and updated you can then open up the tax file you desire.
Once you have the return open make sure to save the return as a PDF file so you can open the return anytime you wish using a PDF reader even if you don't have the program installed any longer.
