Used Pr El 2020 for 1st time today. Created a .prel file, but the program will not re-open the .prel

Used Pr El 2020 for 1st time today. Made a project and created a .prel file. Then I closed the program. Five minutes later I try to reopen the file but Pr El 2020 does not recognize it! It will not re-open the .prel file I created five minutes ago. I did not move any of the component files. Help!