You pose a question with limited information.
You had to download Turbo Tax in order to file
Did you download to your PC or your MAC?
On the MAC go to the finder icon and open and your find Turbo Tax 2018
On the PC go to Start...click Control Panel....look for Turbo Tax
Also...on the PC....click on upper left "file" and lock to see if you can click on "Open Recent"
Good luck